Answer:
heat energy
Explanation:
Friction causes the molecules on rubbing surfaces to move faster, so they have more energy. This gives them a higher temperature, and they feel warmer.
It was D. Miguel Hidalgo but i could be wrong..
Answer:
a. 
b. Δ
c. 
Explanation:
a).
Momentum conserved





b).
Δ


Δ
c).


d).
All of which has been lost as mechanical energy, and is now thermal energy warmer football players, noise a loud crunch for example.