Determine the value of the potential energy of an arrow weighing 30 g before the shot if it flew out at a speed of 100 m / s.

According to the law of conservation of energy,
Energy does not go anywhere, and is not taken from the air. It only passes from one to the other. For example, the kinetic energy of an ejected arrow will gradually turn into potential.
By finding kinetic energy at the beginning, we can find potential energy at the highest point
Eк = Ep
Ek = m * V ^ 2/2
We just have to substitute the values, but first we will convert 30 grams into kilograms
30 grams = 0.03 kilograms
And it turns out
Eк = 0.03 * 100 ^ 2/2 = 150 (J)
Eк = Ep = 150 (J)
Answer: Ep = 150 (J)