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IB Physics HL A.2.1 Newton’s Three Laws of Motion

Practise analysing HL force systems, including variable drag, orbital motion, propulsion and action-reaction pairs.

Syllabus
First assessment 2025
Course
Physics HL
Level
HL

Exam points

  • Analyse force diagrams and resultant forces in non-uniform and circular motion.
  • Explain propulsion, drag and orbital force situations using Newton’s laws.
  • Distinguish action-reaction pairs from balanced forces in complex systems.

A.2.1—Newton’s three laws of motion question 1

[Maximum number: 2]

This question is about the forces on a skier.

A skier is pulled up a hill by a rope at a steady velocity. The hill makes an angle of 12∘12^{\circ} with the horizontal. The mass of the skier and skis is 73 kg . The diagram below shows three of the forces acting on the skier.

Figure for Question A.2.1—Newton’s three laws of motion question 1 — IB Physics HL

Explain, using Newton's first law of motion, why the resultant force on the skier must be zero.

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