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1 markEffects of Forces

CAPE Physics Unit 1 · 2012 · Paper 2 · Question 4(b)(i)

A rock of density 2500 kg m⁻³ with volume 0.002 m³ falls from rest in a viscous medium. The rock is acted on by a net constant downward force of 30 N (a combination of the gravitational force and a buoyant force F_b) and a viscous retarding force F_d, proportional to its velocity, v: F_d = 5v.

Draw a free body diagram showing the forces acting on the rock.

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Other parts of this question

  1. 4(a)State Newton's 2nd law of motion.[1 mark]
  2. 4(b)(ii)Explain what is meant by a 'viscous medium'.[2 marks]
  3. 4(c)(i)Calculate the mass of the rock.[10 marks]
  4. 4(c)(ii)Calculate the buoyant force, F_b.[1 mark]
  5. 4(c)(iii)Calculate the initial acceleration of the rock.[1 mark]
  6. 4(c)(iv)Calculate the terminal velocity of the rock.[1 mark]
  7. 4(d)Sketch graphs to show how the (i) velocity and (ii) acceleration of the rock vary with time.[2 marks]

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