Hi there!
We can use the conservation of angular momentum to solve.

I = moment of inertia (kgm²)
ω = angular velocity (rad/sec)
Recall the following equations for the moment of inertia.

Begin by converting rev/sec to rad sec:

According to the above and the given information, we can write an equation and solve for ωf.

It is also likely (but not certain) that the photons will be absorbed by atoms. ... Light particles( or photons) never”run out” or loose their energy, so they can go an infinite distance, or until it reaches an object, that reflects the light or obsorbs it. Ie, a planet, or a mirror.
The formula for a kinetic energy KE of a falling body is
KE = mgh
where m = mass, g = acceleration due to gravity (9.8 m/s^2, constant), h = height.
The total mass of a skateboader and a skateboard is 64 + 2.0 = 66 kg.
Finally,
KE = 66*9.8*5.0 = 32340 J
Explanation:
Mass of the crate, m = 68 kg
We need to find the resulting acceleration if :
(a) Force, P = 0
P = m a
⇒ a = 0
(b) P = 181 N



(c) P = 352 N



Hence, this is the required solution.