µ IB | Forces

10 quick questions



10 minutes maximum! (can you do it in 5?)




 1. When drawing an arrow to show the size of the force of gravity on a falling meteor, which of these images shows the correct placement for the arrow?

2. The force of gravity as shown by the arrow in Q1 can be labelled in many ways. Which of these is likely to marked as incorrect?

  • A. weight
  • B. mg
  • C. gravity
  • D. downwards force of gravity from the Earth

3. Which of these diagrams correctly shows the size of the forces on the meteor as it is moving at a very high velocity downwards but slowing down due to air resistance? The meteor has been drawn as a point.

Q4&5. The diagram below shows a stationary block on a slope.

4. Which of the 4 diagrams correctly shows a free body diagram for all the forces acting on the block?


5. In which direction is the resultant force acting in question 4?

  • A. Up the slope.
  • B. Down the slope.
  • C. Towards the centre of the Earth.
  • D. There is no resultant force.


6&7. These questions are about friction:


6. The symbol µs in the IB data book refers to the quantity.....

  • A. the force of friction.
  • B. the coefficient of static friction.
  • C. the efficiency of friction
  • D. the frictional constant

7. If µd is equal to 0.5, this means that the maximum force produced by friction on a moving object is half the size of....

  • A. the weight of the object.
  • B. the driving force moving the object.
  • C. the reaction force of the surface on the object.
  • D. the air resistance on the object.



8-10. A book of mass 1.0 kg rests on a rough horizontal surface with µs= 0.4.


What is the value of the reaction force on the book?

  • A. 1.0 N
  • B. 0.4 N
  • C. 10 N
  • D. 4 N

9. What is the maximum frictional force preventing the book moving to the left or right if pushed?

  • A. 1.0 N
  • B. 0.4 N
  • C. 10 N
  • D. 4 N

10. The horizontal surface is raised at one end so that the book rests on a slope. It remains stationary. What happens to the sizes of the reaction force and the maximum force of static friction as the surface is lifted at one end?

Reaction force Maximum force of static friction
decreases decreases
decreases increases
increases decreases
increases increases