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Power and efficiency

Power and efficiency

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Question 9

Two electric water pumps, Pump A and Pump B, are used to lift water vertically from the same depth.

  • Pump A has an efficiency of 60% and is driven by a motor with an input power of PPP.
  • Pump B has an efficiency of 80% and is driven by a motor with an input power of 1.5P1.5P1.5P.

Both pumps run for the same duration of time. Let MA M_A\,MA​ be the mass of water successfully raised by Pump A, and MB M_B\,MB​ be the mass of water successfully raised by Pump B.

Assuming all useful work done by the pumps goes entirely into increasing the gravitational potential energy of the water, which of the following relationships is correct?

A

MB=2MAM_B = 2M_AMB​=2MA​

B

MB=1.5MAM_B = 1.5M_AMB​=1.5MA​

C

MB=1.125MAM_B = 1.125M_AMB​=1.125MA​

D

MB=0.5MAM_B = 0.5M_AMB​=0.5MA​

Markscheme

Power and efficiency Questions

  1. GCSE
  2. /Physics
  3. /Power and efficiency

37 exam-style questions on OCR GCSE Physics Power and efficiency. Each one has a worked solution and a mark scheme showing where the marks go.

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