State two energy resources that do not have the Sun as their original source of energy.
An underwater tidal turbine is used to generate electricity. The useful electrical energy output from the turbine in 1.0 s1.0\text{ s}1.0 s is 15 000 J15\ 000\text{ J}15 000 J. The kinetic energy of the water hitting the turbine in 1.0 s1.0\text{ s}1.0 s is 25 000 J25\ 000\text{ J}25 000 J. The velocity of the water hitting the turbine is 2.2 m/s2.2\text{ m/s}2.2 m/s.
Show that the mass of water hitting the turbine each second is approximately 10 300 kg10\ 300\text{ kg}10 300 kg.
Calculate the efficiency of the turbine.
Solar energy and geothermal energy are both renewable energy resources. Suggest one reason why geothermal energy is a more reliable energy resource than solar energy.
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.