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12 marksMotions

CAPE Physics Unit 1 · 2005 · Paper 2 · Question 4(b)(v)

In a crash test, a car of mass 1200 kg hits a wall and recoils. The initial velocity of the car is 20 m s⁻¹ and it bounces back at 1.5 m s⁻¹ as shown in Figure III. The contact with the wall lasts for 0.18 s.

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 in part (b) (iii) to show how the force varies with time when a car crumples more than the one in the diagram.

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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)(iii)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…[1 mark]
  4. 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]
  5. 4(b)(i)What is the change of momentum of the car during this collision?[1 mark]
  6. 4(b)(ii)Find the impulse of the force acting on the car.[1 mark]
  7. 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]
  8. 4(b)(iv)Find the average force acting on the car during the collision.[1 mark]

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