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CAPE Physics Unit 1 · 2005 · Paper 2 · Question 4(a)(iii)

Figures II (a) and II (b) show Newton's cradle, an apparatus with 5 identical spheres hung from a frame, used to demonstrate elastic collisions.

TWO of the spheres, each of mass m, are pulled to one side as shown in Figure II (b) and released so that they strike the others with velocity v. A student observing the demonstration predicts that immediately after the collision ONE sphere will move off from the other side with velocity 2v while the first TWO spheres come to rest. Show that this is NOT possible since only one of the two quantities in (a) (ii) is conserved.

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Other parts of this question

  1. 4(a)(i)Define the term 'momentum.'[1 mark]
  2. 4(a)(ii)Which TWO physical quantities are conserved in an elastic collision?[1 mark]
  3. 4(a)(iv)In fact in the above demonstration the incoming spheres come to rest but TWO spheres move off together on the other side with velocity v. Show that BOTH the…[8 marks]
  4. 4(b)(i)What is the change of momentum of the car during this collision?[1 mark]
  5. 4(b)(ii)Find the impulse of the force acting on the car.[1 mark]
  6. 4(b)(iii)Sketch a graph to show the typical variation of force with time during a collision like this and state what the area under the graph represents.[1 mark]
  7. 4(b)(iv)Find the average force acting on the car during the collision.[1 mark]
  8. 4(b)(v)Discuss why modern cars are designed to crumple in a head-on collision. Illustrate your answer with a sketch graph (labelled CRASH 2) using the same scale as…[12 marks]

More practice: the rest of this paper · more Motions questions · all CAPE Physics Unit 1 past papers