Answer to Question #115793 in Physics for Mariya

Question

Q1 Explain why renewable sources provide an increasing fraction of electricity supply for many countries
Q2. A cyclist is riding a bicycle at a steady velocity of 12 m/s. The cyclist and bicycle have a total mass of 68 kg. Describe the energy transfers that happen when the cyclist uses the brakes to stop.

Answer 1

Q1 Because countries understand that the amount of fossil fuels is limited and will not be enough for the next 100 years. Renewable sources, on the contrary, will be enough for many years from now.

Q2 As the cyclist uses the brakes to stop, the kinetic energy of the motion converts to the heat and potential energy of shock absorbers and to the heat of the disk brakes. Also, if the bicyclist cannot stop without slipping, some fraction of his kinetic energy converts to the work done against friction.