What best demonstrates the transformation of mechanical energy to heat energy and light energy?

The movement of electrons demonstrate the best conversion of mechanical into heat energy and light energy .

electrons travels with a velocity so it clearly indicates mechanical energy

while travelling it releases heat energy(dissipation) .In lamps heat energy makes to glow the lamps (which converts heat energy to light energy).

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.