An object of mass 2 kg has a linear momentum of magnitude 6 kg·m/s. What is this object's kinetic energy?

• 3 J

• 6 J

• 9 J

• 12 J

• 18 J

A box with a mass of 2 kg accelerates in a straight line from 4 m/s to 8 m/s due to the application of a force whose duration is 0.5 s. Find the average strength of this force.

• 2 N

• 4 N

• 8 N

• 12 N

• 16 N

A ball of mass m traveling horizontally with velocity v strikes a massive vertical wall and rebounds back along its original direction with no change in speed. What is the magnitude of the impulse delivered by the wall to the ball?

Two objects, one of mass 3 kg and moving with a speed of 2 m/s and the other of mass 5 kg and speed 2 m/s, move toward each other and collide head-on. If the collision is perfectly inelastic, find the speed of the objects after the collision.

• 0.25 m/s

• 0.5 m/s

• 0.75 m/s

• 1 m/s

• 2 m/s

Two objects move toward each other, collide, ad separate. If there was no net external force acting on the objects, but some kinetic energy was lost, then

• the collision was elastic and total linear momentum was conserved

• the collision was elastic and total linear momentum was not conserved

• the collision was not elastic and total linear momentum was conserved

• the collision was not elastic and total linear momentum was not conserved

• None of these

A car of mass 1,000 kg collides head-on with a truck of mass 2,000 kg. Both vehicles are moving at a speed of 21 m/s, and the collision is perfectly inelastic. After the crash, the two vehicles skid to a halt. Assuming friction is the only force acting on the vehicles after the collision, how much work is done by friction after the crash?

• 73,500 J

• -73,500 J

• 147,000 J

• -147,000 J

• 220,500 J

Which of the following best describes a perfectly inelastic collision free of external forces?

• Total linear momentum is never conserved.

• Total linear momentum is sometimes conserved.

• Kinetic energy is never conserved.

• Kinetic energy is sometimes conserved.

• Kinetic energy is always conserved.