ASAP please!
need physics help on test

Avery hard rubber ball (m = 0.5 kg) is falling vertically at 4 m/s just before it bounces on the floor. the ball rebounds back at essentially the same speed. if the collision with the floor lasts 0.05 s, what is the average force exerted by the floor on the ball?

Matter is needed to transfer thermal energy bya. conductionb. convectionc. radiation d. both a & b.

What happens when the number of protons in an atom changes