Edexcel IGCSE Physics 4.17 Power equation

Practise using P = E/t or P = W/t to find power, time, energy or mass flow, with careful conversions between hours, kW and J.

Exam points

substitute energy and time into P = E/t to calculate mean or maximum power
rearrange P = E/t to find time or energy transferred, converting minutes or hours to seconds
combine power with mgh for turbine or water-flow calculations under 100% efficiency

[Maximum number: 3]

Energy is transferred from the Sun to the Earth.

Solar panels use energy from the Sun to heat water.

Figure for Question 4.17 Power equation question 1 — Edexcel IGCSE Physics

The total area of the solar panels is $15 \mathrm{~m}^{2}$ .

Each $1.0 \mathrm{~m}^{2}$ of the solar panels receives 1000 J of energy per second from the Sun. Show that the total energy transferred to the solar panels in 2 hours is about 100 MJ .

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4.17 Power equation question 1