1. friction between water molecules
2. the wave spreads out onto a larger and larger area, so per unit area, the energy of the wave goes down
Answer:
A) A buoy rises in the water as a boat speeds past.
Explanation:
The passing boat transfers energy in the form of a wave. Other options illustrate other physics concepts like gravity (falling egg) or Newton's law (for every action, there is an equal and opposite reaction).
Answer:
(a) 
(b) 
Explanation:
According to Newton's second law:

Recall that the frictional force is related jointly with the coefficient of friction and normal force
. Replacing in the above equation, we get the coefficient of friction:

(a) The coefficient of static friction is related with the force required to set the block in motion:

(b) The coefficient of kinetic friction is related with the force required to keep the block moving with constant speed:
