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1 markEffects of Forces

CAPE Physics Unit 1 · May/June 2022 · Paper 2 · Question 1(b)(ii)

Stokes' law equation F_D = 6 π r η v for a moving spherical object.

State ONE condition under which the equation F_D = 6 π r η v applies for the motion of a spherical object.

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Other parts of this question

  1. 1(a)(i)Define the term 'drag force'.[2 marks]
  2. 1(a)(ii)Define the term 'terminal velocity'.[2 marks]
  3. 1(a)(iii)Define the term 'uniform motion'.[2 marks]
  4. 1(b)(i)State the meaning of EACH term on the right-hand side of the equation F_D = 6 π r η v.[3 marks]
  5. 1(c)(i)On the grid provided in Figure 1 on page 7, plot a graph of velocity, v, against time, t. Draw a smooth curve through the points.[4 marks]
  6. 1(c)(ii)Explain the shape of the graph plotted in (c)(i).[3 marks]
  7. 1(c)(iii)Use the graph in (c)(i) to determine the terminal velocity, v_t, of the metal sphere, in m s⁻¹.[2 marks]
  8. 1(d)(i)Determine the units of k.[3 marks]
  9. 1(d)(ii)Given that m = 5 × 10⁻³ kg and r = 1 × 10⁻³ m, determine the value of k for glycerin at 30 °C.[2 marks]
  10. 1(e)(i)Explain how the terminal velocity will be affected if a sphere of the same mass but twice the radius is used.[2 marks]
  11. 1(e)(ii)Explain how the terminal velocity will be affected if a sphere of a different metal is used.[2 marks]
  12. 1(f)Explain why the upthrust is neglected in the calculation of terminal velocity in this experiment.[2 marks]

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