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Physics
11th -
12thgrade
IB Physics Topic 2 Mechanics (Energy and Momentum)
22 questions
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- 1. Multiple ChoiceA double-ended launching device fires two identical steel balls X and Y at exactly the same time. The diagram shows the initial velocities of the balls. They are both launched horizontally, but Y has greater speed.
Which statement explains what an observer would see?Both X and Y reach the ground simultaneously, because air resistance will cause both to have the same final speed.Both X and Y reach the ground simultaneously, because gravitational acceleration is the same for both.X reaches the ground before Y, because X lands nearer to the launcher.Y reaches the ground before X, because Y has greater initial speed. - 2. Multiple ChoiceAt time t = 0, a body moves from rest with constant acceleration in a straight line. At time t, the body is distance s from its rest position.
A graph is drawn of s against t2, as shown.
Which statement describes the acceleration of the body?It is equal to half the value of the gradient of the graph.It is equal to the value of the gradient of the graph.It is equal to twice the value of the gradient of the graph.It is equal to the reciprocal of the gradient of the graph. - 3. Multiple ChoiceA lift (elevator) consists of a passenger car supported by a cable which runs over a light, frictionless pulley to a balancing weight. The balancing weight falls as the passenger car rises.
What is the magnitude of the acceleration of the car when carrying just one passenger and when the pulley is free to rotate?0.032 ms–20.32 ms–20.6 ms–20.65 ms–2 - 4. Multiple ChoiceA wooden block rests on a rough board. The end of the board is then raised until the block slides down the plane of the board at constant velocity v.
Which row describes the forces acting on the block when sliding with constant velocity?ABCD - 5. Multiple ChoiceTwo spheres travel along the same line with velocities u1 and u2. They collide and after collision their velocities are v1 and v2.
Which collision is not elastic?ABCD - 6. Multiple ChoiceA ball of mass m is thrown up to height h in air with an initial velocity v, as shown.
Air resistance is considered negligible. The acceleration of free fall is g. What is the total work done by the gravitational force on the ball during its flight from P to Q?zero½mv2mgh2 mgh - 7. Multiple ChoiceA spring of unextended length 40 mm is suspended from a fixed point. A load of 16 N is applied to the free end of the spring. This causes the spring to extend so that its final length is five times its original length. The spring obeys Hooke’s Law.
What is the energy stored in the spring due to this extension?
1.3 J1.6 J2.6 J3.2 J - 8. Multiple ChoiceThe diagram shows an arrangement used to find the output power of an electric motor. The wheel attached to the motor’s axle has a circumference of 0.5 m and the belt which passes over it is stationary when the weights have the values shown.
If the wheel is making 20 revolutions per second, what is the output power of the motor?300 W500 W600 W700 W - 9. Multiple ChoiceA ball is dropped from rest at time t = 0 on to a horizontal surface from which it rebounds. Which one of the following graphs best shows the variation of speed v of the ball with time t from the time t = 0 to the time that the ball leaves the surface?ABCD
- 10. Multiple ChoiceWhich one of the following is a true statement concerning the vertical component of the velocity and the acceleration of a projectile when it is at its maximum height?ABCD
- 11. Multiple ChoiceThe area between the line of the graph and the time-axis representsthe average velocity of the object.the displacement of the object.the impulse acting on the object.the work done on the object.
- 12. Multiple ChoiceWhich one of the following graphs shows the corresponding variation with time t of the acceleration a of the object?ABCD
- 13. Multiple ChoiceAn astronaut in outer space is holding a hammer and drifting at constant velocity. The astronaut throws the hammer in the opposite direction to that in which she is drifting. What change, if any, occurs in the total kinetic energy and the total momentum of the astronaut and hammer?ABCD
- 14. Multiple ChoiceA constant force is applied to a ball of mass m. The velocity of the ball changes from v1 to v2 . The impulse received by the ball ism(v2 +v1)m(v2 −v1)m(v22 + v12 )m(v22 − v12 )
- 15. Multiple ChoiceAn electric train develops a power of 1.0 MW when travelling at a constant speed of 50ms−1. The net resistive force acting on the train is . . . .50 MN200 kN20 kN200 N
- 16. Multiple Choice
The efficiency of an electric motor is 20%. When lifting a body 500 J of energy are wasted. What is the useful work done by the motor?
A. 100 J
B. 125 J
C. 250 J
400 J
- 17. Multiple Choice
A motor of input power 160 W raises a mass of 8.0 kg vertically at a constant speed of 0.50 ms^-1. What is the efficiency of the system?
A. 0.63%
B. 25%
C. 50%
D. 100%
- 18. Multiple Choice
A student of weight 600N climbs a vertical ladder 6.0 m tall in a time of 8.0 s. What is the power developed by the student against gravity?
A. 22 W
B. 45 W
C. 220 W
D. 450 W
- 19. Multiple Choice
A moving system undergoes an explosion. What is correct for the momentum and kinetic energy of the system when compared immediately before and after the explosion?
A.
B.
C.
D.
- 20. Multiple Choice
A graph shows the variation of force acting on an object moving in a straight line and the distance moved. Which area represents the work done on the object during its motion from 0 to P?
A. X
B. Y
C. Y+Z
D. X+Y+Z
- 21. Multiple Choice
A stone is dropped from the edge of a cliff. Which of the following graphs best represents the stone's kinetic energy KE as a function of time t?
- 22. Multiple Choice
An object with a mass of 2 kg is initially at rest at a position x = 0. A non-constant force F is applied to the object over 6 meters. What is the velocity of the object at 6 meters?
150 m/s
25 m/s
300 m/s
12.25 m/s
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