# Exercises - Force and Motion 7

1. Which of the following diagrams shows that the 3 forces T, W and R are in equilibrium?
A.
B.
C.
D.

2.
Which of the following diagrams shows the correct vector diagram of the forces acting on the advertisement board above?
A.
B.
C.
D.

3. In the diagram, the 3 forces F1, F2 and 50N are in equilibrium. Find the value of F1.

1. 43.3 N
2. 25.0 N
3. 35.0 N
4. 32.7 N

4. Which of the following statements is true about work done?
1. Work is a vector quantity.
2. Work done can be positive or negative.
3. Work have same unit as the energy.
4. Work is done when a force is applied on an object.

5. The figure shows a 10N force acting on a block. The block moves 5m to the right. Calculate the work done by the force.
1. 50 J
2. -50 J
3. 0 J
4. 25 J

6. A trolley moves against friction of 10N. The initial velocity of the trolley is 5 m/s. The trolley come to rest in 6s. Find the work done to overcome the friction.
1. -150 J
2. -300 J
3. -60 J
4. -50 J

7. A student of mass 50kg does push-ups by applying a force to elevate its center-of-mass by 20cm. Determine the number of push-ups which he must do in order to do a 5000 Joules of work.
50

8. A student pulls a 50 kg box up a smooth plane inclined at 30° to the horizontal as shown in figure above. If the length of the plane is 5 m, find the work done in pulling the box to the top of the plane.
1. 1250 J
2. 2500 J
3. 1500 J
4. 1750 J

9. Determine the kinetic energy of a 600kg car that is moving at a speed of 20.0 m/s.
1. 120,000 J
2. 6,000J
3. 240,000J
4. 60,000J

10. An object of 2kg mass dropped from a height of 2m and then bounced up to a height of 1.5 m. Find the amount energy lost in the process.
1. 10J
2. 40J
3. 30J
4. 50J
5. 70J