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2 marksMotions

CAPE Physics Unit 1 · 2009 · Paper 2 · Question 1(b)(iii)

A model rocket with an initial mass of 1.8 kg is launched vertically. Its mass decreases at a constant rate of 0.25 kg s⁻¹ as fuel burns, reaching a final mass of 0.40 kg. During its flight, the acceleration due to gravity is constant at 9.8 m s⁻².

Calculate the time taken for the fuel to be burned.

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Other parts of this question

  1. 1(a)(i)Write down an equation which shows the relation between the resultant force F on a body, the time t for which the force acts and the change in momentum, Δp, of…[1 mark]
  2. 1(a)(ii)Define the term 'impulse'.[1 mark]
  3. 1(b)(i)Calculate the initial weight of the rocket.[1 mark]
  4. 1(b)(ii)Calculate the final weight of the rocket.[1 mark]
  5. 1(c)(i)On the grid on the page opposite, plot a graph of the upward Force (F)/N versus Time (t)/s. Draw the BEST curve through the points.[3 marks]
  6. 1(c)(ii)On the SAME graph draw a line to represent the variation with time of the total weight of the rocket while the fuel is burning.[2 marks]
  7. 1(c)(iii)From the graph, read off the time delay between the firing of the rocket and lift off. Write this value in the space below.[1 mark]
  8. 1(c)(iv)On the graph, shade the area that represents the change in momentum of the rocket during the first 4 seconds after the rocket is fired.[1 mark]
  9. 1(c)(v)Estimate the value for the change in momentum of the rocket.[2 marks]

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