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1.7 Energy, work and power

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Question 1

A small wind-turbine drives an electric generator.

The wind blows with a velocity of 8.5 m/s at right angles to the plane of the turbine. The mass of air passing per second through the turbine is 9.2 kg.

a.

Calculate the kinetic energy of the air blown through the turbine per second.

[2]
b.

Only 12% of this kinetic energy is converted to electrical energy. Calculate the electrical power output of the generator.

[2]
c.

The volume of air passing through the turbine each second is 7.8 m3. Calculate the density of the air.

[2]
d.

Describe the essential action within the generator that produces electricity.

[3]
Markscheme

1.7 Energy, work and power Questions

  1. IGCSE
  2. /Physics
  3. /1.7 Energy, work and power

533 exam-style questions on CIE IGCSE Physics 1.7 Energy, work and power, covering 1.7.1a Energy stores and energy transfers, 1.7.1b Conservation of energy, 1.7.1c Kinetic and gravitational potential energy, 1.7.2 Work done, 1.7.3 Energy resources, 1.7.3a Energy resources and electricity generation, 1.7.3b Nuclear fusion as an energy source, 1.7.3c Efficiency of energy transfer, and 1.7.4 Power. Each one has a worked solution and a mark scheme showing where the marks go.

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