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2.3.5 Forces and Pulleys

By the end of this lesson you can:

  • Analyse systems connected by ropes and pulleys
  • Apply Newton's second law to each object in a system
  • Calculate acceleration and tension in a pulley system
Find your course: NSW Year 11: Forces and motionNSW Year 12QLD Unit 2: Linear motion and forceVICAP Physics 1: Unit 2IB: A.2 Forces and momentum
🎥 Watch📝 Practise🕹️ Explore🎯 Exam ready🍎 Teachers
🎥Watch
Learn the idea: a short explanation, then a check.
A useful context to examine Newton's Second Law, is the use of pulleys. Simple pulleys, where there is only one wheel, simple change the direction of the force.
​The following are all examples of situations involving pulleys.
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If the masses hanging on pulleys are NOT in equilibrium, the system will accelerate. This video will examine accelerating systems and how to solve them. (for the sake of simplicity, friction in the pulleys is deemed to be negligible)

📝Practise
Worked examples first, then problems to try, then worksheets.
Some problems to try

1. Assuming the surface has negligible friction,
a. determine the acceleration of the system and the tension on the rope (1.63 ms-2, 0.82 N)
b. If the surface in the above question has a μ = 0.1, what will be the new acceleration? (0.82 ms-2)
c. The box sudden encounters a section of the surface that has a μ = 0.3. Explain what occurs.

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2. Determine the acceleration if μ = 0.15. (3.54 ms-2)

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🕹️Explore
Test your predictions in a simulation.