Yes. Kinetic energy is a form of mechanical energy and friction will turn that kinetic energy into heat.
Hydroelectricity is the best answer.
This is an article by the EIA, but the pie graph is the most helpful: https://www.eia.gov/energyexplained/?page=us_energy_home
Answer:
c. The group speed is less than the phase speed.
Explanation:
For an individual the speed is given by v phase = w/k
w is angular frequency and k is wave number.
This is called phase speed. Group speed is the speed of wave packet.The rate of advance of a crest on a single wave point which is fixed phase.
Gravitational force of attraction between two objects can be calculated from the following formula:

Where m with subscript stands for mass of the object and r is the distance between them.
When we double the mass of those two objects, distance between them stays the same, while in the numerator we have:

When numerator in the second case 4 times greater than the 'original' numerator and denominator stays the same, force becomes 4 times greater.