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IB Physics SL A 2 7 Frictional Force Questions

Practise applying static and dynamic friction to blocks, slopes, circular motion and accelerating systems.

Syllabus
First assessment 2025
Course
Physics SL
Level
SL

Exam points

  • Apply the parallel-contact friction model, distinguishing static friction up to μsFN from dynamic friction μdFN.
  • Calculate a friction force or coefficient from an inclined-plane or horizontal-surface situation, including the limiting angle or onset of sliding.
  • Determine how friction changes the acceleration, stopping distance or motion of a sliding object.
  • Analyse friction between coupled bodies or between an object and a moving surface, including whether slipping occurs.
  • Use static friction to determine limiting conditions in circular motion, such as the minimum angular speed needed to prevent sliding.

Learn this topic

Study A.2.7—Frictional force conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Physics SL A 2 7 Frictional Force Questions question 1

[Maximum number: 3]

A student strikes a tennis ball that is initially at rest so that it leaves the racquet at a speed of 64 m s−164 \mathrm{~m} \mathrm{~s}^{-1}. The ball has a mass of 0.058 kg and the contact between the ball and the racquet lasts for 25 ms .

The student models the bounce of the tennis ball to predict the angle θ\theta at which the ball leaves a surface of clay and a surface of grass.

Figure for Question IB Physics SL A 2 7 Frictional Force Questions question 1 — IB Physics SL

The model assumes
- during contact with the surface the ball slides.
- the sliding time is the same for both surfaces.
- the sliding frictional force is greater for clay than grass.
- the normal reaction force is the same for both surfaces.
Predict for the student's model, without calculation, whether θ\theta is greater for a clay surface or for a grass surface.

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