physics chapter 7

three objects are moving along a straight line as shown in the figure. taking the positive direction to be to the right, what is the total momentum of this system?

-14.0kg*m/s

a 0.14-kg baseball is dropped from rest from a height of 2.0 m above the ground. what is the magnitude of its momentum just before it hits the ground if we neglect air resistance?

0.88kg*m/s

If you want to double the momentum of a gas molecule, by what factor must you increase its kinetic energy?

4

There must be equal amounts of mass on both sides of the center of mass (or center of gravity) of a system.

False

In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is Before After 3.0m/s. 1.5m/s 1.8m/s 1.8m/s 2kg 8kg 2kg 8kg

completely inelastic

Identical forces act for the same length of time on two different objects. The magnitude of the change in momentum of the lighter object is

exactly equal to the magnitude of the change in momentum of the larger mass.

The momentum of an isolated system is conserved

in both elastic and inelastic collisions

A railroad car collides with and sticks to an identical railroad car that is initially at rest. After the collision, the kinetic energy of the system

is half as much as before

which of the following quantities are units of momentum? (there could be more than one answer)

kg*m/s N*s

In the figure showing an isolated system, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is

not possible because momentum is not conserved.

An egg falls from a bird's nest in a tree and feels no effects due to the air. As it falls,

only its mechanical energy is conserved

In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is before after 1.8m/s 0.2m/s 0.6m/s 1.4m/s 4kg 6kg 4kg 6kg

partially inelastic

If you want to double the kinetic energy of a gas molecule, by what factor must you increase its momentum?

square root of 2

Two objects of different masses have equal, non-zero kinetic energies. Which object has the greater magnitude momentum?

the heavier object

Two objects of different masses have momentum of equal, non-zero magnitude. Which object has more kinetic energy?

the lighter object

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

the momentum of the car-truck system is conserved, but the momentum of each one separately is not conserved.

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?

the small car and the truck experience the same average force

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

the small car and the truck experience the same magnitude momentum change.

in a collision between two unequal masses, which mass receives a greater magnitude impulse?

they receive equal impulses.