Please help me please?

Question

So i have this huge assignment due and i have been working on it for 3 days and there are 3 questions on the thing i just cant get. i dont know if its just because i have been looking at for so long or what but please help.
1- an object with a of mass of 2.12kg is attached to a string to be used as a pendulum. The object is raised above its initial position so that its potential energy is 3.74 J higher than when the object is in its lowest position. The object is released and begins to move. How fast is the object moving when it gets back to its lowest position?

2-Describe the energy conversions for the process that begins at a power plant and eventually turns a ceiling fan.

3- describe energy conversions for the process that begins when a person eats food and ending with that person running.

Please help me. Any help will be appriciated. If you know #1 can you also let me know the work/ equation used to get the answer so i understand it thanks.

thanks for answering #1 i knew it had to be changed to a different form of energy but beyond that i had no clue

Answer 1

Here's number 1.

You are told that the potential energy difference between the release point and the lowest point is 3.74 J. ALl of that has to be in the form of kinetic energy when the pendulum is at its lowest point. So

3.74 J = 1/2 mv^2 ---> v =sqrt(2*3.74/2.12) = 1.88 m/s