Science Homework Help

hey!! I was looking online and found 2 questions on the law of conservation of energy and don’t fully get them.

1. A stretched bow holds an arrow in place; The electric potential energy “stored” in the bow is 54J.

a) If the 0.45kg arrow is released then what speed will it reach

b) if a force of 360N is required to stretch the bow, what is the extension length

2. A ball is rolling along a track on the ground. The track then follows a sloped ramp. Halfway up the ramp, the balls speed is 5.6m/s. Find the height reached by the ball, ignoring friction.

and last thing, I was curious about, if a ball is dropped from a really tall tower, and at a time in its descent, reaches a point where it doesn’t accelerate anymore, is the mechanical energy conserved?