Well energy absorption by a material depends upon their atomic properties. Energy is absorbed in discrete quanta of energy as predicted by quantum mechanics only if the corresponding energy state is available either it is absorbed by electrons or nucleus depends whether it can go to permissible energy state, if not system can't absorb energy at all.
Because it’s cheaper and efficient
Answer:
a. 
b. 21.64 m/s
Explanation:
Let g = 9.81m/s2
a. The weight of the block is product of its mass and gravitational acceleration

which is also the normal force acting on the block from the floor so it stays balanced.
N = 71.225N
The static friction of the block is product of its normal force from the floor and the friction coefficient

For the block to move, the force generated by the impact must be at least equal to the static friction.

The impulse is product of this force and time duration of impact.

As impulse is generated by change in momentum of the ball, which is product of its mass and velocity v



b. 