A block with mass m = 4.90 kg is placed against a spring on a frictionless incline with angle θ = 45° (The block is not attached to the spring). The spring, with spring constant k = 35.0 N/cm, is compressed 16.0 cm and then released.a.) What is the elastic potential energy of the compressed spring?b.) What is the change inn the gravitational potential energy of the block-Earth system as the block moves from the release point to its highest point on the incline?c.) How far along the inline is the highest point from the release point?

Answers

Answer 1

Answer:

a) 44.8J

b) 44.8J

c) 127cm

Explanation:

a) The elastic potential energy of a compressed spring is given by the formula:

[tex]U_e=\frac{1}{2} kx^{2}[/tex]

Where U_e is the elastic potential energy, k is the spring constant and x is the distance the spring is compressed. In this case, we have:

[tex]U_e=\frac{1}{2} (35.0N/cm)(16.0cm)^{2} = 4480Ncm[/tex]

To express the result in Joules, we have to use the fact that 1cm=0.01m. Then:

[tex]U_e=4480Ncm=4480N(0.01m)=44.8J[/tex]

In words, the elastic potential energy of the compressed spring is 44.8J.

b) Using the law of conservation of mechanical energy, we have that:

[tex]E_o=E_f\\\\U_{eo}+U_{go}+K_o=U_{ef}+U_{gf}+K_f[/tex]

Taking t=0 the moment in which the block is released, and t=t_f the point of its maximum height, we have that [tex]U_{g0}=0;K_0=0;U_{ef}=0;K_f=0[/tex] because in t=0 the block has no speed and is in tis lowest point; and in t=t_f the block has stopped and isn't in contact with the spring. So, our equation is reduced to:

[tex]U_{gf}=U_{e0}\\\\U_{gf}=44.8J[/tex]

So, the gravitational potential energy of the block in its highest point is 44.8J.

c) Using the gravitational potential energy formula, we have:

[tex]U_g=mgh\\\\\implies h=\frac{U_g}{mg} \\\\h=\frac{44.8J}{(4.90kg)(9.8m/s^{2}) }=0.9m=90cm[/tex]

Using trigonometry, we can compute the distance between the release point and its highest point:

[tex]d=\frac{h}{sin\theta}=\frac{90cm}{sin45\°}=127cm[/tex]


Related Questions

Two hypothetical discoveries in Part A deal with moons that, like Earth's moon, are relatively large compared to their planets. Which of the following best explains why finding 1 planet with such a moon is consistent with the nebular theory, while finding 6 planets with such moons is not consistent?

Answers

Answer:

Explanation:

Solution:

- Finding large moons comparable in size to their planets result from impacts of two astro-bodies. The probability of such an event occurring is very rare.

- Even at the best luck, one moon can be made from the result of giant impact. While the probability of 6 planets having moons of comparable sizes is close to impossible.

During oxidation-reduction reactions, a material loses electrons to the oxidizer, which has a positive charge. Which power source directs these lost electrons through an electronic device to give it power?

A. An electric outlet
B. An electromagnet
C. An electric motor
D. A battery

Answers

Answer:

D. Battery

During the oxidation-reduction(redox) reaction, there is always flow of electrons from one point to another. The electrons are then converted to power through the battery which converts chemical energy to electrical energy. If there is zero flow of electrons then there will also be zero power.

Answer:

D. A battery.

Explanation:

A battery cell refers to a single anode and cathode separated by electrolyte used to produce a voltage and current. It is typically an electrolytic cell.

An electrolytic cell is an electrochemical cell that drives a non-spontaneous redox reaction through the application of electrical energy. They are often used to decompose chemical compounds, in a process called electrolysis.

The anode which is positive electrode undergoes oxidation i.e loss of electrons while the cathode(negative) undergoes reduction that is, accept electrons.

A 328-kg car moving at 19.1 m/s in the + x direction hits from behind a second car moving at 13.0 m/s in the same direction. If the second car has a mass of 790 kg and a speed of 15.1 m/s right after the collision, what is the velocity of the first car after this sudden collision?

Answers

Final answer:

To find the velocity of the first car after the collision, we can use the principle of conservation of momentum.

Explanation:

To find the velocity of the first car after the collision, we can use the principle of conservation of momentum. The total momentum before the collision is equal to the total momentum after the collision.

Before the collision:

Total momentum = (mass of first car × velocity of first car) + (mass of second car × velocity of second car)

After the collision:

Total momentum = (mass of first car × velocity of first car after collision) + (mass of second car × velocity of second car after collision)

Using the given information and the principle of conservation of momentum, we can solve for the velocity of the first car after the collision.

Learn more about Momentum here:

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A 1.44-mole sample of an ideal gas is allowed to expand at a constant temperature of 258 K. The initial volume is 14.5 L and the final volume is 27.0 L. How much work does the gas perform on its container? Let the ideal-gas constant R = 8.314 J/(mol • K).

1920 J

2340 J

1550 J

1040 J

Answers

Answer:

1920 J

Explanation:

Answer:

19.6 L

Explanation:

In this process we have an isothermal process, a transformation in which the temperature of the gas remains constant.

In an isothermal process, the work done by the ideal gas on the surrounding is:

[tex]W=nRT ln\frac{V_f}{V_i}[/tex]

where:

n is the number of moles of the gas

R is the gas constant

T is the absolute temperature of the gas

[tex]V_i[/tex] is the initial volume of the gas

[tex]V_f[/tex] is the final volume

In this problem, we have:

n = 1.44 mol

T = 258 K is the gas temperature

[tex]V_i=14.5 L[/tex] is the initial volume of the gas

[tex]V_f=27.0 L[/tex] is the final volume

Solving the equation for W, we find the work done by the gas:

[tex]W=(1.44)(8.314)(258)ln\frac{27.0}{14.5}=1920 J[/tex]

A particle of mass 4.5 × 10-8 kg and charge +5.4 μC is traveling due east. It enters perpendicularly a magnetic field whose magnitude is 2.7 T. After entering the field, the particle completes one-half of a circle and exits the field traveling due west. How much time does the particle spend in the magnetic field?

Answers

Answer:

0.00970 s

Explanation:

The centripetal force that causes the charge to move in a circular motion = The force exerted on the charge due to magnetic field

Force due to magnetic field = qvB sin θ

q = charge on the particle = 5.4 μC

v = velocity of the charge

B = magnetic field strength = 2.7 T

θ = angle between the velocity of the charge and the magnetic field = 90°, sin 90° = 1

F = qvB

Centripetal force responsible for circular motion = mv²/r = mvw

where w = angular velocity.

The centripetal force that causes the charge to move in a circular motion = The force exerted on the charge due to magnetic field

mvw = qvB

mw = qB

w = (qB/m) = (5.4 × 10⁻⁶ × 2.7)/(4.5 × 10⁻⁸)

w = 3.24 × 10² rad/s

w = 324 rad/s

w = (angular displacement)/time

Time = (angular displacement)/w

Angular displacement = π rads (half of a circle; 2π/2)

Time = (π/324) = 0.00970 s

Hope this Helps!!!

A student sits on a rotating stool holding two 2.6 kg masses. When his arms are extended horizontally, the masses are 0.71 m from the axis of rotation, and he rotates with an angular velocity of 1.8 rad/sec. The student then pulls the weights horizontally to a shorter distance 0.23 m from the rotation axis and his angular velocity increases to ω2. For simplicity, assume the student himself plus the stool he sits on have constant combined moment of inertia Is = 3.8 kg m2 . Find the new angular velocity ω2 of the student after he has pulled in the weights. Answer in units of rad/s.

Answers

Answer:

2.8 rad/s

Explanation:

In absence of external forces, the total angular momentum of the system must be conserved.

The angular momentum when the arms of the student are extended horizontally is given by:

[tex]L_1 = (I_0 + 2I)\omega_1[/tex]

where:

[tex]I_0=3.8 kg m^2[/tex] is the moment of inertia of the student+stool

[tex]I=mr^2[/tex] is the moment of inertia of each mass, where:

m = 2.6 kg is one mass

r = 0.71 m is the distance of each mass from the rotation axis

[tex]\omega_1=1.8 rad/s[/tex] is the initial angular velocity

So we have

[tex]L_1=(I_0+2mr^2)\omega_1[/tex]

When the student pulls the weights to a distance of r' = 0.23 m, the angular momentum is:

[tex]L_2=(I_0+2I')\omega_2[/tex]

where:

[tex]I'=mr'^2[/tex] is the new moment of inertia of each mass, with

r' = 0.23 m

Since the angular momentum must be constant, we have:

[tex]L_1=L_2\\(I_0+2mr^2)\omega_1 = (I_0+2mr'^2)\omega_2[/tex]

and solving for [tex]\omega_2[/tex], we find the final angular velocity:

[tex]\omega_2 = \frac{I_o+2mr^2}{I_0+2mr'^2}\omega_1=\frac{3.8+2(2.6)(0.71)^2}{3.8+2(2.6)(0.23)^2}(1.8)=2.8 rad/s[/tex]

(1 point) A spotlight on the ground is shining on a wall 20m20m away. If a woman 2m2m tall walks from the spotlight toward the building at a speed of 0.8m/s,0.8m/s, how fast is the length of her shadow on the building decreasing when she is 8m8m from the building

Answers

Answer:

The answer to the question is;

When she is 8 m from the building fast the length of her shadow on the building is decreasing at [tex]\frac{2}{9} m/s[/tex] or 0.22 m/s.

Explanation:

We have

Distance of the spotlight from the building = 20 m

Distance  of woman from the building when her speed is measured = 8 m

Height of the woman = 2 m

Actual speed of the woman = 0.8 m/s

Comparing the distance of the woman from the spotlight and the wall from the spotlight, we have when the woman is 8 m from the building she is 12 m from the spotlight    

Therefore we have

[tex]\frac{12}{20} = \frac{2}{y}[/tex] where y is the shadow cast by the woman on the building = 10/3

When the woman is x distance from the building, she is 20 - x meters from the spotlight

Therefore the above equation can be written  as

[tex]\frac{20-x}{20} = \frac{2}{y}[/tex]  which gives [tex]1 - \frac{1}{20}*x = 2* \frac{1}{y}[/tex] finding the derivative of both sides gives

[tex]-\frac{1}{20}dx =-2*\frac{1}{y^2}dy[/tex] hence we have by dividing by dt gives [tex]-\frac{1}{20}\frac{dx}{dt} =-2*\frac{1}{y^2}\frac{dy}{dt}[/tex]

However we know that [tex]\frac{dx}{dt} = 0.8 m/s[/tex]

Therefore [tex]-\frac{0.8}{20} = -0.18\frac{dy}{dt}[/tex]

The rate of decrease of her shadow [tex]\frac{dy}{dt}[/tex] is given by

[tex]\frac{dy}{dt} = \frac{0.8}{3.6} =\frac{2}{9} m/s[/tex] or 0.222 m/s.

a cart mass 3kg rolls down a slope. when it reaches the bottom a spring loaded gun fires a 0.5kg ball with horizontal velocity 0.6m/s. find final velocity of the cart

Answers

Answer:

the final velocity of the cart is 5.037m/s

Explanation:

Using the conservation of energy

[tex]T_a + V_a = T_b + V_b[/tex]

[tex]T_a = \frac{1}{2} (m_c + m_b)v_a^2[/tex]

[tex]T_a= \frac{1}{2} (3 + 0.5)(0)^2[/tex]

= 0

[tex]V_a = (m_c + m_b)gh_a[/tex]

[tex]V_a = (3 + 0.5) * 9.81 * 1.24[/tex]

[tex]= 42.918J[/tex]

[tex]T _b = \frac{1}{2} (3 + 0.5)v_b^2 \\\\ = 1.75v_b^2[/tex]

[tex]V_b = (3 + 0.5) * 9.81 * 0\\ = 0[/tex]

[tex]T_a + V_a = T_b + V_b\\ 0 + 12.918 = 1.75v_b^2 + 0\\v_b = 4.95m/s[/tex]

Using the conservation of linear momentum

[tex](m_c + m_b)v_B = m_cv_c + m_bv_b\\(3 + 0.5) * 4.95 = 3v_c - 0.5v_b\\17.33 = 3v_c - 0.5v_b\\v_b = 6v_c - 34.66 ...............(1)[/tex]

[tex]Utilizing the relative velocity relation = v_b - v_c\\-0.6 = -v_b - v_c\\v_b = 0.6 - v_c (2)[/tex]

equate (1) and (2)

[tex]6v_c - 34.66 = 0.6 - v_c\\7v_c = 35.26\\v_c = 5.037m/s[/tex]

the final velocity of the cart is 5.037m/s

Two boxes connected by a light horizontal rope are on a horizontal surface. The coefficient of kinetic fric-tion between each box and the surface is ilk = 0.30. Box B has mass 5.00 kg, and box A has mass m. A force F with magnitude 40.0 N and direction 53.1° above the horizontal is applied to the 5.00-kg box, and both boxes move to the right with a = 1.50 m/s2. A) What is the tension T in the rope that connects the boxes? B) What is m?

Answers

Given, Two boxes(Let's say A and B) are connected horizontally by a light rope. Coefficient of kinetic friction between each box is 0.30. Mass of Box B is 5.00 kg and Box A is 'm'. The force is 40.0 N in the direction [tex]53.1^{o}[/tex].

To find the tension in the rope and the mass of one of the boxes, Newton's Second Law is applied separately to each box, accounting for tension, friction, and the applied force. By resolving the applied force and calculating the friction, we can solve for tension and then for the unknown mass.

To solve for these, we must apply Newton's Second Law of Motion (F = ma) to each box separately.

Part A: Tension T in the Rope

For Box B (5.00 kg), which has the force applied:

Resolve the applied force F into horizontal [tex](F_{x})[/tex] and vertical [tex](F_{y})[/tex] components.Calculate the friction force [tex](f_{k})[/tex] acting against Box B using the coefficient of kinetic friction (μ) and the normal force (N).Write Newton's Second Law for horizontal motion, accounting for tension (T), friction [tex](f_{k})[/tex], and the applied force component [tex](f_{x})[/tex].Solve for tension (T) based on the known acceleration (a) and the mass of Box B.

Part B: Mass m of Box A

For Box A (with unknown mass m):

Calculate the friction force [tex](f_{k})[/tex] acting against Box A using μ_k and the weight (mg).Apply Newton's Second Law for Box A, considering only tension (T) and friction [tex](f_{k})[/tex].Solve for the unknown mass (m) based on the calculated tension (T) and the known acceleration (a).

Appropriate use of Newton's laws and kinetic friction calculations will yield answers to both parts of the question.

Cathy, a 460-N actress playing Peter Pan, is hoisted above the stage in order to "fly" by a stagehand pulling with a force of 60. N on a rope wrapped around a pulley system. What is the actual mechanical advantage of the pulley system?

Answers

Answer:7.67

Explanation:

Given

Weight of Cathy [tex]W_1=460\ N[/tex]

Force exerted by rope [tex]F=60\ N[/tex]

Mechanical advantage is the ratio of load by Pulling effort      

[tex]M.A.=\frac{Load}{Pulling\ effort}[/tex]

[tex]M.A.=\frac{460}{60}[/tex]

[tex]M.A.=7.67\ N[/tex]

Final answer:

The actual mechanical advantage of the pulley system that hoists Cathy is calculated by dividing the load force (460 N) by the effort force (60 N), resulting in an actual mechanical advantage of approximately 7.67.

Explanation:

The actual mechanical advantage (MA) of a pulley system is the ratio of the load force to the effort force. Given that Cathy, a 460-N actress, is raised with an effort of 60 N, we can calculate the actual mechanical advantage by using the formula MA = Load/Effort. By dividing 460 N by 60 N, we get an actual mechanical advantage of approximately 7.67. This implies that the pulley system is using 7.67 times less effort force to lift the load, thus increasing the efficiency of the task.

Pulley systems can provide significant mechanical advantage by allowing a smaller effort force to move a larger load. This effectiveness is heightened if the pulleys are arranged in such a way as to multiply the tension in the ropes as they support the load. With perfectly friction-free pulleys and ropes, the MA can be simply counted as the number of ropes supporting the load, making the force output nearly an integral multiple of the input force.

What are the correct methods of heat transfer

Answers

Conduction, Convection, and Radiation

Explanation:

The transfer of heat generally depends on the difference in the temperature in the surroundings.

The best methods for the transfer of heat are conduction convection, radiation and sometimes evaporation also.

Conduction: This is the transfer of heat through the system that is solid. Convection: Convection is the process in which warm surfaces of a liquid or gas rises to cooler surfaces in the liquid or gas that is the transfer of heat from the surface. Natural convection occurs as air is heated: it expands, rises, and is replaced by cooler air. Radiation: This is a process where energy is radiated among the surroundings in the form of electromagnetic radiation. Evaporation: The latent heat of a liquid is used to transfer heat by absorbing the energy needed to evaporate that liquid. The heat absorbed is released by condensing the liquid outside the enclosure.

Answer:Condution radiation convection

Explanation:

A 1500 kg car skids to a halt on a wet road where μk = 0.47. You may want to review (Pages 141 - 145) . Part A How fast was the car traveling if it leaves 68-m-long skid marks?

Answers

Final answer:

To find the initial velocity of a 1500 kg car that left 68-m-long skid marks, the kinetic energy (½mv²) equal to the work done by friction is used, resulting in the equation v = √(2μkgd). Plugging in the values gives the car's speed.

Explanation:

To determine how fast a 1500 kg car was traveling before it skidded to a halt on a wet road with a coefficient of kinetic friction (μk) of 0.47, leaving 68-meter-long skid marks, we can use the work-energy principle. The kinetic energy the car had before skidding must equal the work done by friction to halt the car.

Work done by friction (W) = μk × normal force (N) × distance (d)

Since the normal force (N) is equal to the weight of the car (mg) where ‘m’ is the mass of the car and ‘g’ is the acceleration due to gravity, normal force can be replaced in this equation:

W = μk × mg × d

The kinetic energy (KE) the car initially had is given by:

KE = ½ m × v2

Setting work done by friction equal to kinetic energy:

½ m × v2 = μk × mg × d

We can then solve for velocity (‘v’), which ends up being:

v = √(2 × μk × g × d)

By plugging in the values (m = 1500 kg, μk = 0.47, g = 9.8 m/s2, d = 68 m) we get the initial velocity.

Calculation:

v = √(2 × 0.47 × 9.8 m/s2 × 68 m)

After completing the calculation, we can determine the car's initial velocity that resulted in the 68-m-long skid marks on the wet road.

You put a 3 kg block in the box, so the total mass is now 8 kg, and you launch this heavier box with an initial speed of 4 m/s. How long does it take to stop

Answers

Answer:

0.7 secs

Explanation:

In this question, the speed does not change as the mass changes. So we can use

Δt=Δ∨x/χgμ............................equ 1

To stop, the final speed will be 0

Therefore,

Δvx=vf-vt

Δvx=0-4m/s

=     -4m/s

Now substitute the various values in equ 1

Δt=Δ∨x/χgμ

Δt=  -4m/s/(9.8m/s∧2) (0.6)

Δt=0.7 secs

Answer:

Explanation:

The box stops at zero speed.

Final Velocity = 0 ,Initial speed (s)= -4 m/s

Therefore=  change in velocity =  Vf - Vi.  ( 0 m/s- 4 m/s) =  -4 m/s

Change in velocity  = -0.4 m/s

Gravity  g = 9.8 m/s^2

Mass= 0.8 g

-4 ms divided by 9.8 ms^2 * (0.8) = 0.51 s

It takes 0.51 seconds to stop

when an object gets larger, why does the volume of an object increase faster than the surface area?

Answers

Let us consider the object to be a cell.

Explanation:

As a cell grows bigger, its internal volume enlarges and the cell membrane expands. This results in the increase in volume more rapidly than does the surface area, and so the relative amount of surface area available to pass materials to a unit volume of the cell steadily decreases. This means the surface area to the volume ratio gets smaller as the cell gets larger.

Example of a cube:

Cube size            Surface area                   Volume

2cm                      2 × 2 × 6 = 24 cm²         2 × 2 × 2 = 8 cm³

4 cm                      4 × 4 × 6 = 96 cm²         4 × 4 × 4 = 64 cm³

6 cm                      6 × 6 × 6 = 216 cm²       6 × 6 × 6 = 216 cm³

8 cm                      8 × 8 × 6 = 384 cm²       8 × 8 × 8 = 512 cm³

This shows as the object gets larger, the volume of an object increases faster than the surface area.

You hold a metal ring horizontally above a bar magnet standing on its end. You drop the ring and catch it before it reaches the magnet. When, if ever, is a current induced in the ring?

Only when the ring stops falling

only when the ring starts falling

while the ring is falling

never, current is not induced

Answers

Answer:

never, current is not induced

Explanation:

The induced emf in the ring equals the rate of change of magnetic flux in the ring.

E = -dФ/dt = -dAB/dt = -BdA/dt since B the magnetic field is constant.

E = -BdA/dt

Now dA/dt = dA/dy × dy/dt where dA/dy = rate of change of area with vertical distance as the ring is falling. dy/dt = speed of ring.

Since the ring is falling freely before being caught, its speed v is gotten from v = u + at where u = 0 and a = -g

v = 0 - gt = -gt

v = -gt  

So, dA/dt = dA/dy × dy/dt = vdA/dy = -gtdA/dy

So E = -BdA/dt = -B × -gtdA/dy = BgtdA/dy

Since dA/dy = 0 since the area of the ring does not change with vertical distance. So,

E = BgtdA/dy = Bgt × 0 = 0

E = 0

So, emf is never induced because the flux through the ring remains constant

A supersonic jet is at an altitude of 14 kilometers flying at 1,500 kilometers per hour toward the east. At this velocity, how far will the jet fly in 1.6 hours?

Answers

Answer:

The jet will fly 2400 km.

Explanation:

Given the velocity of the jet flying toward the east is 1,500 kmph toward the east.

We need to find the distance covered in 1.6 hours.

In our problem we are given speed and time, we can easily determine the distance using the following formula.

[tex]Distance=Speed\times Time[/tex]

[tex]Distance=1500\times 1.6=2400\ km[/tex]

So, the supersonic jet will travel 2400 km in 1.6 hours toward the east from its starting point.

Two boxes connected by a light horizontal rope are on a horizontal surface. The coefficient of kinetic fric-tion between each box and the surface is ilk = 0.30. Box B has mass 5.00 kg, and box A has mass m. A force F with magnitude 40.0 N and direction 53.1° above the horizontal is applied to the 5.00-kg box, and both boxes move to the right with a = 1.50 m/s2. A) What is the tension T in the rope that connects the boxes? B) What is m?

Answers

Answer:

(A). The tension in the rope that connects the boxes is 10.50 N.

(B). The value of m is 7 kg.

Explanation:

Given that,

Mass of box B = 5.00 kg

Mass of box A = m

Force = 40.0 N

Direction= 53.1°

Acceleration = 1.50 m/s²

Coefficient of kinetic friction = 0.30

(A). We need to calculate the tension in the rope that connects the boxes

Using balance equation

[tex]T=ma+m\cos\theta[/tex]

Put the value into the formula

[tex]T=5\times1.50+5.00\cos53.1[/tex]

[tex]T=10.50\ N[/tex]

(B). We need to calculate the value of m

Using formula of tension

[tex]T=ma[/tex]

[tex]m=\dfrac{T}{a}[/tex]

Put the value into the formula

[tex]m=\dfrac{10.50}{1.50}[/tex]

[tex]m=7\ kg[/tex]

Hence, (A). The tension in the rope that connects the boxes is 10.50 N.

(B). The value of m is 7 kg.

Which of the following best defines a nation's labor force? the total number of persons who are willing and able to work but cannot find a job the total number of persons between the ages of 16 and 65 the total number of employed and unemployed persons the total number of persons working full time and part time

Answers

Answer:

the total number of persons between the ages of 16 and 65

Explanation:

The labour force consists of all the people who are able to work in a country or area, or all the people who work for a particular company.

The workforce of a country includes both the employed and the unemployed (labour force)

Final answer:

The labor force of a nation includes all employed and unemployed persons, excluding those not actively seeking work. Employed individuals have a job, while unemployed individuals are jobless but actively looking for work. The unemployment rate measures the percentage of the labor force that is unemployed.

Explanation:

A nation's labor force is best defined as the total number of employed and unemployed persons. Specifically, it includes all individuals who are either currently working (employed) or actively seeking employment (unemployed). The labor force does not include those who are not seeking work, such as students, stay-at-home parents, individuals with disabilities preventing them from working, or those who have taken early retirement.

The unemployment rate is a key economic indicator that represents the percentage of the labor force that is unemployed. It's important to note that to be considered unemployed, a person must be actively looking for work and available to work. This excludes people who are not actively seeking employment, who are then categorized as out of the labor force.

Lastly, the definition of 'employed' in the United States is quite broad, including those working part-time or temporarily, as well as individuals on leave but who have a job.

When you jump from a height to the ground, you let your legs bend at the knees as your feet hit the floor.Why we do this in terms in physics in momentum?

Answers

Final answer:

Bending the knees when landing from a jump increases the impact time and decreases the force experienced by the body, as per the impulse-momentum theorem. This technique prevents injuries by distributing the force over a longer period, thus reducing the force's intensity on the bones.

Explanation:

When we jump from a height to the ground and bend our knees upon landing, we are effectively reducing the impact force experienced by our body. This is explained by the impulse-momentum theorem, which states that the change in momentum (or impulse) of an object is equal to the force applied multiplied by the time the force is applied. The momentum of a person jumping from a height is quite large due to their mass and the speed at which they are moving toward the ground due to gravity. If we land with straight legs, that momentum is transferred very quickly to our legs and the ground, which results in a very high force over a short time. This can lead to injuries as bones can fracture if the force on them is too large.

By bending our knees, we increase the time over which our momentum is brought to zero, which means the force exerted on our legs and subsequently on the bones is lessened, as force is inversely proportional to the time over which the momentum changes. This principle applies to various real-world situations like rolling on the ground after a jump, using a parachute, or even the crumple zones in cars, all designed to extend the impact time and reduce the force felt by the occupants.

The gravitational attraction between Earth and the person causes the person to accelerate towards the Earth. However, due to Earth's significantly greater mass, Earth's movement is negligible compared to that of the person. This results in the person experiencing a much greater acceleration and subsequently a larger change in momentum when they hit the ground after a jump.

Harbor seals, like many animals, determine the direction from which a sound is coming by sensing the difference in arrival times at their two ears. A small difference in arrival times means that the object is in front of the seal; a larger difference means it is to the left or right. There is a minimum time difference that a seal can sense, and this leads to a limitation on a seal's direction sense. Seals can distinguish between two sounds that come from directions 3∘ apart in air, but this increases to 9∘ in water.Explain why you would expect a seal's directional discrimination to be worse in water than in air.

Answers

Answer:

that the angle must be increased to maintain the minimum time of discrimination due to the increase in the speed of sound in material

Explanation:

The direction of sound is detected by the difference in time of reception of each ear, the speed of the wave is

             v = d / t

             t = d / v

In air the velocity is v = 330 m / s, let's use trigonometry

           Cos 3 = d / L

           L = d / cos 3

The difference in distance is

            Δd = d - d / cos 3 = d (1- 1 / cos3)

             t = Δd / 330

When the animal is in the water the speed of sound is

              v = 1540 m / s

So time is

             t' = Δd ’/ 1540

            t ’= Dd’ / 4.67  330

So if  t = t’  is the minimum response time, the distance must be increased

            Δd ’= 4.6 Δd

            1-1 / cos θ = 4.6 (1- 1 / cos 3) = -4.6 0.00137 = -0.00631

           1 + 0.0063 = 1 / cos θ

           1.00631 = 1 / cos θ

           Cos θ = 1 / 1.00631

           Tea = 6.5

We see that the angle must be increased to maintain the minimum time of discrimination due to the increase in the speed of sound in material

A woman fires a rifle with barrel length of 0.5400 m. Let (0, 0) be where the 125 g bullet begins to move, and the bullet travels in the +x-direction. The force exerted by the expanding gas on the bullet is (16,000 + 10,000x − 26,000x2) N, where x is in meters. A) Determine the work done by the gas on the bullet as the bullet travels the length of the barrel.
B) If the barrel is 1.05 m long, how much work is done?

Answers

Final answer:

The work done by the gas on the bullet while the bullet travels the length of a 0.54m barrel was calculated to be 9,354.80 joules, and the work done for a 1.05m barrel length was calculated to be -5,712.50 joules.

Explanation:

The work done by the force of the gas on the bullet can be determined by calculating the integral of the force with respect to x, from 0 to the length of the barrel. The force is a function of x, F(x) = 16,000 + 10,000x - 26,000x^2. The work done W = ∫F(x) dx, from x = 0 to x = 0.54 m.

By integrating this function we have, W = 16,000x + 5,000x^2 - 26,000x^3/3. Substituting the upper and the lower limits in, we get W = 9,354.80 joules.

For part B) we calculate work using the same formula but changing the length of the barrel to 1.05 m. The Calculated work done by the gas on the bullet, when the length of the barrel is 1.05 m, is W = -5,712.50 joules. Here, negative work signifies that the bullet is working against the direction of the force.

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Final answer:

To compute the work done by the gas on the bullet as it travels the length of the barrel, we use an integral to sum the work done over the length of the barrel. The force function given is integrated across the range from 0 to the length of the barrel (either 0.5400 m or 1.05 m).

Explanation:

The work done by a variable force in one-dimension can be computed using the formula:

Work = ∫F(x) dx

Where F(x) is given as (16,000 + 10,000x - 26,000x^2) N and the limits of the integral are from 0 to the length of the barrel. For a 0.5400 m barrel, we evaluate the integral with these limits. Similar for the second part, using 1.05 m as the upper limit.

The actual calculations would involve integrating the function for force (F), and then substituting the limits of 0 and 0.5400 m or 1.05 m in the result to calculate the work done.

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You throw a ball straight upward. As it leaves your hand, its speed is 15 m/s. (a) How much time does it take for the ball to reach the top of its trajectory? Start from a fundamental principle and show all your work.

Answers

Answer:

the ball takes 1.53 s to reach the top of its trajectory.

Explanation:

given information:

the speed, v = - 15 m/s (moving upward)

(a) How much time does it take for the ball to reach the top of its trajectory?

we know that the speed for the vertical motion is

v = v₀ - gt, v₀ = 0

where

v = speed (m/s)

g = gravitational force (9.8 m/s²)

t = time (s)

thus

v = - gt

-15 = - 9.8 t

t = 15/9.8

 = 1.53 s

so, the time that is needed by the ball to reach the top its trajectory is 1.53 s

Answer:

The ball takes 1.53 seconds to reach its top trajectory

Explanation:

The velocity of the ball will keep pushing it upwards until the velocity becomes zero. Therefore, the ball will reach the top of its trajectory when velocity i.e. V=0,

Fundamental principal of velocity is V = Vo + g*t

where, V=0  

Vo = 15 m/s

g = -9.8 m/s^2 (since ball is going upwards against the gravity)

t = ?  

0 = 15 + (-9.8 * t)

-15 = -9.8t

-15 / -9.8 = t

t = 1.53 Seconds

The ball takes 1.53 seconds to reach its top trajectory

If the equipotential surfaces due to some charge distribution are vertical planes, what can you say about the electric field direction in this region: (a) it is vertically upward, (b) it is vertically downward, (c) it is horizontally to the left, (d) it is horizontally to the right, or (e)either (c) or (d) could be correct?

Answers

Answer:

The correct option is

(e)either (c) or (d) could be correct.

Explanation:

The electric field of a charge radiates out in all directions and the intensity of the electric field strength given by E = F/q₀, diminishes as the lines of force moves further away from the source. The direction of F and E is in the line of potential motion of the source charge in the field.

Equipotential surfaces are locations in the radiated electric that have the same field strength or electric potential. The work done in moving within an equipotential surface is zero and as such since

Work = Force × distance = 0 where distance ≠ 0.

The force acting between two points on an equipotential surface is also zero or the component of the force within an equipotential surface is zero and since there is a force in the electric field, it is acting at right angles to the equipotential surface which could be horizontally to the left or right directions where the equipotential surfaces due to the charge distribution are in the vertical plane.

Therefore it is either horizontally to the left, or horizontally to the right.

LC oscillators have. been used to circuits. connected to loud speakers to create some of the sounds of electronic musc. What indductance must be usedd with a 6.7 uF capacito r to prodice a frequncy of 10

Answers

Answer:

[tex]3.8\times 10^{-8}\ H[/tex]

Explanation:

Given the [tex]6.7\mu F[/tex] capacitor is used in an LC circuit to produce [tex]10\ kHz[/tex] frequency.

We need to find the value of inductance required.

As we know the relation between angular frequency in [tex]rad/sec[/tex] and frequency in [tex]Hz[/tex] is.

[tex]\omega =2\times \pi\times f[/tex]

Where [tex]\omega[/tex] is angular frequency and [tex]f[/tex] is frequency.

[tex]\omega=2\times \pi\times 10\times 1000=20000\pi\ rad/sec\\\omega=62832\ rad/sec[/tex]

Also, the relation between the angular frequency, capacitance and inductance is given by.

[tex]\omega^2=\frac{1}{LC}\\\\L=\frac{1}{\omega^2C} \\\\L=\frac{1}{62832^2\times6.7\times 10^{-6} } \\\\L=\frac{1}{26451}.\\ \\L=3.8\times 10^{-8}\ H[/tex]

So, [tex]3.8\times 10^{-8}\ H[/tex] inductance will be required to produce [tex]10\ kHz[/tex].

The 38-mm-diameter shaft ab is made of a grade of steel for which the yield strength is 250 mpa. v y using the maximum-shearing-stress criterion, determine the magnitude of the torque t for which yield occurs when p 240 kn.

Answers

Answer:

Answer is 717 N . m

Refer below for the explanation.

Explanation:

As per the question,

38 mm diameter shaft,

Yield strength 250 mpa,

P 240kn.

Refer to the picture for complete explanation.

Final answer:

The maximum torque that the steel shaft can withstand before yielding, according to the maximum-shearing-stress criterion, is 8224 N.m.

Explanation:

The problem can be solved by first calculating the maximum shear stress that the steel shaft can withstand before yielding. The shear strength is given by the yield strength divided by the square root of 3, as the maximum-shearing-stress criterion indicates that failure occurs when the maximum shear stress equals half the yield stress. Therefore, the shear strength τ of the steel shaft is τ = 250 MPa/√3 = 144.34 MPa.  

Next, we can find the maximum torque T that the shaft can handle before yielding by using the formula T=τ*J/r, where J is the polar moment of inertia and r is the radius. Because the shaft is a circular cross section, its polar moment of inertia J = π*r⁴/2. Substituting the given diameter of the shaft d=38mm, we find r = d/2 = 19mm, so J = π*(19mm)⁴/2 = 1075.21 mm⁴.  

Thus, the critical torque T causing yield by the maximum-shearing-stress criterion can be calculated: T = τ*J/r = (144.34 MPa)*(1075.21 mm⁴)/(19 mm)=8224 N.m

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A mass M is attached to spring, which exerts no force at position C. The spring is compressed until the mass is in position A. Then the mass is released. At what position is the velocity at a maximum and positive? At what position is the acceleration at a maximum and positive?

Answers

Answer:

Maximum velocity: Position C, Maximum positive acceleration: Position A.

Explanation:

Let consider that spring is compressed in the negative direction. Then, the maximum velocity occurs at position C, when spring is not compressed nor stretched. Since force in spring is of reactive nature, that is, the direction of force is opposed to the direction of movement, a maximum positive acceleration occurs at position A.

Tony drove to the mountains last weekend. There was heavy traffic on the way there, and the trip took hours. When Tony drove home, there was no traffic and the trip only took hours. If his average rate was miles per hour faster on the trip home, how far away does Tony live from the mountains? Do not do any rounding.

Answers

Answer:

Question not completed, so I analysed the question first

Tony drove to the mountains last weekend. there was heavy traffic on the way there, and the trip took 6 hours. when tony drove home, there was no traffic and the trip only took 4 hours. if his average rate was 22 miles per hour faster on the trip home, how far away does tony live from the mountains?

Explanation:

Let use variables to solve the problems

Let the first trip to be mountain take x hours

Let the trip back home take y hours

Let the speed to while going to the mountain be a miles/hour

Then, while going home it was b miles/hour faster than while going to the mountain.

Then, speed going home is (a+b)miles / hour

The formula for speed is given as

Speed=distance/time

The constant through out the journey is distance, the two journey has the same distance.

Then,

Distance =speed×time

For first journey going to the mountain

Distance = a×x=ax miles

For the second journey going home

Distance =y×(a+b)

Distance Mountain= distance home

ax=y(a+b)

Make a subject of the formula

ax=ya+yb

ax-ya=yb

a(x-y)=yb

a=yb/(x-y)

Therefore, distance from mountain is

Distance=speed ×time

Distance= a×x=ax

Now, applying the questions

So from the questions

x=6hours, y=4hours

Also, b=22miles/hour

Then,

a=yb/(x-y)

a=4×22/(6-4)

a=88/2

a=44miles/hour

Then, the house distance from the mountain is

Distance=ax

Distance =44×6

Distance =264miles

Answer:

480 miles.

Explanation:

Let, S = rate on his way to the mountains.

Assume, Sgoing x time going = Sreturning x time returning

= S × 12 hours = (S + 20mph) ×8 hours

= 12 × S = 8 × S + 160.

4 × S = 160

S = 40 miles/hour

The trip took 12 hours at 40 miles per hour, so distance was:

= 12 hours × 40 mph

= 480 miles.

The loss of an electron from a neutral helium atom results in

Answers

An cation. This is because the helium atom now has a positive charge

The electrode comes into direct contact with the workpiece, and some degree of force is applied Group of answer choices Electron Beam Welding (EBW) Gas Tungsten Arc Welding (GTAW) Resistance Spot Welding (RSW) Laser Welding (LBW) Plasma Arc Welding (PAW) Oxyacetylene Welding (OAW)

Answers

Answer:

Gas Tungsten Arc Welding (GTAW) Resistance Spot Welding (RSW)

Explanation:

Only the Gas tungsten arc welding and the spot resistance welding have a physical electrode and both of them make a contact with the work-piece. Both of the techniques use a non-filling electrode that generates heat energy into the welding area of the work-piece. In the GTAW the tungsten electrode is brought directly into the contact of two closely spaced interfaces of the work-piece and the electric current generated by the arc produced and  the inert gas (usually argon) is used to shield the welding zone to prevent the oxidation of the material. A force of compressive nature is applied on the joint to keep the fused material at the joint to complete the welding. This welding process is also called Tungsten inert gas welding.

In the spot resistance welding the electrode comes into contact with the pieces of the workpiece (usually thin sheets upto 3mm) from both the sides of the workpiece and generates the heat of electric power without any spark intended. The filler material may be placed between the two joining pieces. This generates only the weld spots and not a continuous wekd seam.

In the other welding techniques the heat is generated via the non-solid energy beams such as electron beam in EBM, plasma in PAW, gas flame in Oxyacetylene welding.

A speedboat accelerates at 2m/s^2. If the boat starts from rest, how fast will the boat be traveling, in m/s, if it accelerates for 5s? Make sure you use the correct unit for your answer and do not put a space between the number and the unit.

Answers

The boat travels with a speed of 10m/s

Explanation:

Given-

Acceleration, a = 2m/s²

Time, t = 5s

Speed, s = ?

We know,

[tex]Acceleration = \frac{speed}{time} \\\\s = at[/tex]

[tex]s = 5 * 2m/s\\s = 10m/s[/tex]

Therefore, Boat travels with a speed of 10m/s

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