Question

1. Linear Momentum of an object is conserved

1. At all times    b. Only when the net external force on the object is Zero

3. When the net external torque on the object is Zero    d. Never

2. A truck of mass 4000 (kg) is moving at 10 (m/s). A car of mass 1000 (kg) is moving at 40 (m/s).

So, the truck’s momentum, compared to the car, is

1. Greater    b. Smaller    c. the same      d. Cannot say without knowing their accelerations

3. A 1000 (kg) car is travelling at 60 (mph) when it collides with a 4000 (kg) truck travelling at 50 (mph) in the same direction. The time of impact between the two vehicles is 50 (ms). Ignoring friction, what is the velocity of the two vehicles after collision if they are stuck?

1. 52 (m/s)       b. 52 (mph)     c. 24 (m/s)      d. 24 (mph)      e. 0

4. In the above, what is the force of collision on the car from the truck?

1. 1,440,000 (N)    b. 400,000 (N)     c. 320,000 (N)       d. 0

5. In question (4), the force of collision on the truck from the car is

1. Greater        b. Smaller       c. The same as      d. Zero

than the force of collision on the car from the truck

6. Angular Momentum of an object is

1. Mass of the object times its velocity
2. Mass of the object times its angular velocity
3. Rotational Inertia of the object times its angular velocity
4. Rotational Inertia of the object times the Angle of rotation

7. A figure skater goes around the ice rink in a circular path with her arms and legs extended out from the axis of rotation. When she pulls her arms and legs towards her body, her angular velocity

1. Increases        b. Decreases        c. Stays the same       d. Cannot say without knowing her mass

8. When work is done on an object, it can be converted to energy. Under ideal conditions, the work done is

1. Greater than the energy        b. Equal to the energy
2. Smaller than the energy        d. Greater or smaller than the energy depending on Mass

9. The above is a result of the

1. Conservation of Mass          b. Conservation of Momentum
2. Conservation of Energy       d. All of the above

10. A pump lifts 1000 (liters) of water from ground to a tank on the roof of a building 100 (m) high. What is the potential energy in the water? [ 1 (liter) = 1000 cm³ ]. Show all your steps to the solution.

11. A skier is coming downhill. At one point she is 50 (m) above the bottom of the hill and moving at 20 (m/s). What is her speed as she reaches the bottom of the hill?

1. 22.3 (m/s)       b. 37.5 (m/s)       c. 44.8 (m/s)       d. Cannot say without her mass

12. A car of mass 1000 (kg) and moving at 60 (mph) collides with a barrier and comes to a stop in

0.5 (s). Ignoring friction, what is the value of the force that acts on the car?

1. 0        b. 20,000 (N)      c. 450, 000 (N)      d. 900,000 (N)

13. A coil spring has an elastic constant of 200 (N/m). If it is compressed by 20 (cm), what is the energy stored in the spring?

1. 4 (J)       b. 10 (J)        c. 20 (J)        d. 40 (J)

14. A 60 (kg) sprinter starts from rest and reaches a speed of 12 (m/s) in 6 (s). What is the power that she must have to reach this speed?

1. 720 (J)      b. 720 (W)       c. 1440 (W)       d. 4320 (J)

15. In the gym a weight-lifter lifts a 50 kg barbell straight up a distance of 50 cm in 0.5 s. What is the work done by the weight-lifter?

1. 25 (W)            b. 250 (J)       c. 250 (W)        d. 500 (J)

16.In the above question, what is Power of the weight-lifter?

1. 25 (W)           b. 250 (J)       c. 250 (W)       d. 500 (W)

17.Consider the following situations.

1. A ball moving at a speed “v” is brought to rest
2. The same ball is thrown from rests o that it moves at speed “v”
3. The same ball is moving at speed “v” is brought to rest and reversed in direction to move at speed “v”

In which case does the ball undergo the largest change in momentum?

1. I      b. I and ii      c. i, ii and iii      d. ii and iii      e. iii

18. A cart moving at a velocity “v” collides with an identical stationary cart on air track. The two carts stick together after collision. What is their combined velocity after the collision?

1. v      b. 0.5 v      c. 0      d. – 0.5 v      f. Need more information

19. Two cars, one twice the mass of the other, are stationary on a horizontal road. A person pushes each car separately with the same with the same force for 5 (s). One can say that the momentum of the lighter car compared to the momentum of the heavier car after 5 (s) is

1. Smaller        b. Larger       c. Same

20. A simple pendulum is pulled up in an arc and let go from a stationary position. As it swings back and forth

1. Its kinetic energy (KE) converts to potential energy (PE)    b. Its PE converts to KE

c. Its Potential Energy Converts to Elastic Energy (EE)   d. Its EE converts to KE  

e. Its EE converts to PE