Final answer:
The claim that kinetic energy was converted to sound energy is supported by the evidence of the bike slowing down as Ellen heard the gravel crunch.
Step-by-step explanation:
The best piece of evidence that supports the claim that kinetic energy was converted to sound energy while Ellen's bike was on the gravel is that Ellen's bike slowed down as she heard the gravel crunch.
When Ellen's bike was rolling on the gravel, the friction between the bike tires and the gravel surface caused a decrease in the bike's speed, which is an indication of the conversion of kinetic energy into sound energy.
The sound of the gravel crunching beneath Ellen's tires is the result of the conversion of kinetic energy from the bike's motion into sound energy that is produced by the compression and release of air molecules in the gravel.
Learn more about Conversion of kinetic energy to sound energy