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# a freight car moves along a frictionless level railroad track at constant speed. the freight car is open on top. a large load of coal is suddenly dumped into the car. what happens to the speed of the freight car?

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### James

Guys, does anyone know the answer?

get a freight car moves along a frictionless level railroad track at constant speed. the freight car is open on top. a large load of coal is suddenly dumped into the car. what happens to the speed of the freight car? from EN Bilgi.

## Solved A freight car moves along a frictionless level

Answer to Solved A freight car moves along a frictionless level

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## Opent top freight train with coal

Question 3 text A freight car moves along a frictionless level railroad track at constant speed. The car is open on top. A large load of coal is suddenly...

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Introductory Physics Homework Help

## Opent top freight train with coal

Thread starter 12boone Start date Oct 10, 2008 Oct 10, 2008 #1 12boone

Question 3 text A freight car moves along a frictionless level railroad track at constant speed. The car is open on top. A large load of coal is suddenly dumped into the car. What happens to the velocity of the car?

It remains the same.

It decreases. <-----

cannot be determined from the information given

Oct 10, 2008 #2 Rake-MC

Looks good to me. Use conservation of momentum to confirm.

m2 is greater than m1 therefore v has to decrease.

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## Chapter 7: Linear Momentum

75 Questions | Total Attempts: 268

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1.

What is the SI unit of momentum?

A. N*m B. N/s C. N*s D. N/m 2.

When a cannon fires a cannonball, the cannon will recoil backward because the

A.

Energy of the cannonball and cannon is conserved.

B.

Momentum of the cannonball and cannon is conserved.

C.

Energy of the cannon is greater than the energy of the cannonball.

D.

Momentum of the cannon is greater than the energy of the cannonball.

3.

A freight car moves along a frictionless level railroad track at constant speed. The car is open on top. A large load of coal is suddenly dumped into the car. What happens to the velocity of the car?

A. It increases. B.

It remains the same.

C. It decreases. D.

Cannot be determined from the information given.

4.

A child falls sideways off a sled while sledding on frictionless ice. What happens to the velocity of the sled?

A. It increases. B.

It remains the same.

C. It decreases. D.

Cannot be determined from the information given.

5.

A rubber ball and a lump of putty have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The putty sticks to the wall. Which objects experiences the greater momentum change?

A. The ball B. The putty C.

Both experience the same momentum change.

D.

Cannot be determined from the information given.

6.

A sailboat of mass m is moving with a momentum p. How would you represent its kinetic energy in terms of these two quantities?

A. (p^2)/(2m) B. (1/2)mp^2 C. Mp D. Mp/2 7.

If you pitch a baseball with twice the kinetic energy you gave it in the previous pitch, the magnitude of its momentum is

A. The same. B. 1.41 times as much. C. Doubled. D. 4 times as much. 8.

The area under the curve on a Force versus time (F vs. t) graph represents

A. Impulse. B. Momentum. C. Work. D. Kinetic energy. 9.

Which of the following is an accurate statement?

A.

The momentum of a projectile is constant.

B.

The momentum of a moving object is constant.

C.

If an object is acted on by a non-zero net external force, its momentum will not remain constant.

D.

If the kinetic energy of an object is doubled, its momentum will also double.

10.

A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the average collision force is correct?

A.

The truck experiences the greater average force.

B.

The small car experiences the greater average force.

C.

The small car and the truck experience the same average force.

D.

It is impossible to tell since the masses and velocities are not given.

11.

Two equal mass balls (one red and the other blue) are dropped from the same height, and rebound off the floor. The red ball rebounds to a higher position. Which ball is subjected to the greater magnitude of impulse during its collision with the floor?

A.

It's impossible to tell since the time intervals and forces are unknown.

B.

Both balls were subjected to the same magnitude impulse.

C. The blue ball D. The red ball 12.

A Ping-Pong ball moving east at a speed of 4 m/s, collides with a stationary bowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experiences the greater magnitude impulse during the collision?

A.

Neither; both experienced the same magnitude impulse.

B. The Ping-Pong ball C. The bowling ball D.

It's impossible to tell since the velocities after the collision are unknown.

13.

Two objects collide and bounce off each other. Linear momentum

A.

Is definitely conserved.

B.

Is definitely not conserved.

C.

Is conserved only if the collision is elastic.

D.

Is conserved only if the environment is frictionless.

14.

A 3.0-kg object moves to the right at 4.0 m/s. It collides head-on with a 6.0-kg object moving to the left at 2.0 m/s. Which statement is correct?

A.

The total momentum both before and after the collision is 24 kg*m/s.

B.

The total momentum before the collision is 24 kgoem/s, and after the collision is 0 kg*m/s.

C.

The total momentum both before and after the collision is zero.

D.

None of the above is true.

15.

A 100-kg football linebacker moving at 2.0 m/s tackles head-on an 80-kg halfback running 3.0 m/s. Neglecting the effects due to digging in of cleats,

A.

The linebacker will drive the halfback backward.

B.

The halfback will drive the linebacker backward.

Source : www.proprofs.com

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James 5 month ago

Guys, does anyone know the answer?