A construction worker puts 20 J of energy in to one strike of his hammer on the head of a nail. The energy transferred to driving the nail into the wood is 8.0 J. What is the efficiency of the construction worker's hammering? (2 sig figs and answer in a percentage)

When a bicycle coasts uphill, it moves slower and slower as it climbs. why? a. its kinetic energy is transforming into heat energy. b. its potential energy is transforming into kinetic energy. c. its kinetic energy is transforming into potential energy and heat energy. d. its potential energy is transforming into kinetic energy and heat energy.