## Concepts to Consider

Possibly useful information:

v = x / t a = v / t

v = vi + a t

v = r F = ma F12 = - F21

w = m g

g = 9.8 m/s2 => 10 m/s2

(that is, use the approximation that g = 10 m/s 2 )

W = F d

P = W / t W = KE

KE = (1/2) m v2

PEg = m g h PEel = (1/2) k x 2

For every question, also consider as a possible answer

E) none of the above 1. A moving object on which no forces are acting will continue to move with constant

A) acceleration

B) speed

C) velocity

D) all of these

2. A rifle recoils from firing a bullet. The speed of the rifle's recoil is small because the

A) force against the rifle is smaller than against the bullet.

B) momentum is mainly concentrated in the bullet.

C) rifle has more mass than the bullet.

D) momentum of the rifle is smaller.

3. Two objects, A and B, have the same size and shape, but A is twice as heavy as B. When they are dropped simultaneously from a tower, they reach the ground at the same time, but A has a greater

A) speed

B) acceleration

C) kinetic energy

D) all of the above

4. A car traveling along the highway needs a certain amount of force exerted on it to stop. More stopping force may be required when the car has

A) more mass

B) more velocity

C) less stopping distance

D) all of the above

5. Consider pushing two objects: If you push object one twice as far as object two while applying the same force you do

A) half as much work as you do to object two

B) the same amount of work as you do to object two

C) twice as much work as you do to object two

D) four times as much work as you do to object two

6. Consider pushing two objects: If you push object one just as far as object two but apply twice the force to object one, you do

A) half as much work as you do to object two

B) the same amount of work as you do to object two

C) twice as much work as you do to object two

D) four times as much work as you do to object two

7. Exert 2 N for a distance of 2 m in 2 s and you deliver a power of

A) 0.5 W

B) 1.0 W

C) 2.0 W

D) 3.0 W

8. Exert 100 J in 50 s and your power output is

A) 0.5 W

B) 1.0 W

C) 2.0 W

D) 4.0 W

9. An object is raised above the ground gaining a certain amount of potential energy. If the same object is raised twice as high it gains

A) half as much energy

B) the same amount of energy

C) twice as much energy

D) four times as much energy

10. An object that has kinetic energy must be

A) elevated

B) falling

C) moving

D) at rest

11. An object that has potential energy may have this energy because of its

A) speed

B) acceleration

C) momentum

D) position

12. A person can lift containers a vertical distance of 1 meter or can roll them up a 2 meter-long ramp to the same elevation. With the ramp, the applied force required is about

A) one-fourth as much

B) half as much

C) the same

D) twice as much

13. When a car is braked to a stop, its kinetic energy is transformed to

A) energy of motion

B) heat energy

C) stopping energy

D) potential energy 14. For which positiondoes the ball on the end of the string have the greatest gravitational potential energy?

20. For which position above does the ball on the end of the string have the greatest kinetic energy?

15. Which requires more work: lifting a 5 kg sack vertically 2 meters or lifting a 10 kg sack vertically 4 meters?

A) lifting the 5 kg sack

B) both require the same amount of work

C) lifting the 10 kg sack

16. A 10 kg sack is lifted 2 meters in the same time as a 5 kg sack is lifted 4 meters. The power expended in raising the 10 kg sack compared to the power used to lift the 5 kg sack is

A) half as much

B) the same

C) twice as much

D) four times as much

17. A 2 kg mass is held 4 m above the ground. What is the approximate potential energy of the mass with respect to the ground?

A) 8 J

B) 40 J

C) 80 J

D) 160 J

18. A 2 kg mass has 40 J of potential energy with respect to the ground. Approximately how far is it located above the ground?

A) 1 m

B) 2 m

C) 3 m

D) 4 m

25. Using 1,000 J of work, a model elevator is raised from the ground floor to the second floor in 20 seconds. How much power does the elevator use?

A) 50 W

B) 500 W

C) 2 kW

D) 20 kW

26. A car moves 3 times as fast as another identical car. Compared to the slower car, the faster car has

A) the same kinetic energy

B) 3 times the kinetic energy

C) 9 times the kinetic energy

D) 12 times the kinetic energy

27. A car moving at 50 km/hr skids 20 m with locked brakes. How far will the car skid with locked brakes if it is traveling at 100 km/hr?

A) 40 m

B) 60 m

C) 80 m

D) 120 m

30. If an object has kinetic energy, then it also must have

A) momentum

B) velocity

C) speed

D) all of the above

45. Put a pipe over the end of a wrench when trying to turn a stubborn nut on a bolt, to effectively make the wrench handle twice as long, you'll increase the torque by A) two
torque = rotational force = force x lever arm

If we make the lever arm twice as great, we increase the torque by two.

B) four

C) eight

D) sixteen

47. To pry open the top of a can of paint, it is best to use a screwdriver that has a handle that is

A) long and thin

B) thick or wide

C) short and stubby

D) slippery

48. A 1-kg rock is suspended from the tip of a meter stick at the 0- cm mark so that the meter stick balances like a see-saw when the fulcrum is at the 25-cm mark. From this information, what is the mass of the meter stick? A) 0.25 kg

B) 0.50 kg

C) 1.00 kg

D) 2.00 kg

49. A car travels in a circle with constant speed. The net force on the car is

A) directed forward, in the direction of travel.

B) directed towards the center of the curve.

C) zero because the car is not accelerating.

D) directed backward, because of friction 50. One end of a long uniform log is raised to shoulder level. Another identical log is raised at its center to the same level. Raising the second log requires about

A) half as much work

B) the same work

C) twice as much work

D) four times as much work

All credit for these questions goes to