Exercises - Force and Motion 7

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

Which of the following diagrams shows the correct vector diagram of the forces acting on the advertisement board above?

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.

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