1.In which situation is work NOT done?

1. a server supports a tray while walking through a restaurant
2. a boy pushes a car, but it doesn't move
3. an ice skater is gliding at a constant velocity
4. all of the above

2.In which situation is work being done?

1. a lawnmower is being pushed forward
2. brakes are slowing a car to a stop
3. neither a nor b
4. both a and b

3.Power is defined as the _______ is done.

a. amount of work which

b. direction at which work

c. angle at which work

d. the rate at which work

4. A student with a mass of 62 kg walks up a flight of stairs with a height of 3.4 meters. How can he decrease his power?

a. walk slower

b. walk faster

c. carry his friends books

5.During the Powerhouse lab, Jack and Jill ran up the hill. Jack is twice as massive as Jill; yet Jill ascended the same distance in half the time.

a. Who did the most work? ______________

b. Who delivered the most power? ______________

c. Explain your answers. ____________________________________________________________________________

6. A construction worker pushes a wheelbarrow 5.0 m with a horizontal force of 50.0 N. How much work is done by the worker on the wheelbarrow?

7. A horizontal force of 200 N is applied to move a 55 kg television set across a 3 m level surface. What is the work done on the television set?

8.A wagon is pulled at a speed of 0.40 meters/sec by a horse exerting an 1,800-newton horizontal force. What is the power of this horse?

9.If a small machine does 2,500 joules of work on an object to move it a distance of 100 meters in 10 seconds, what is the force needed to do the work? What is the power of the machine doing the work?

10.What does momentum NOT depend upon?

1. mass
2. time
3. velocity
4. inertia

11.Mechanical energy is not conserved when...

1. gravitational potential energy is converted to kinetic energy.
2. kinetic energy is converted to gravitational potential energy.
3. kinetic energy is converted to elastic potential energy.
4. friction is not negligible.

12. Calculate the impulse of a puck if a hockey stick exerts a force of 120 N on a puck during the 0.05 seconds of contact.

13. During an automobile crash test, a 1000 kg car is sent towards a cement wall at a speed of 14 m/sec and is brought to a stop in 0.08 seconds. What was the average force e of the car on the wall?