Question

A 0.34 kg pendulum bob is attached to a string 1.2 m long. What is the change in the gravitational potential energy of the system as the bob swings from the bottom of the string, where θ = 37°?

i don't know how to do this. The bottom of the string is 1.2 m and it moves 37°...

Answer 1

Use trigonometry to figure out the displacement in the y direction

(1.2 m) * (cos 37) = displacement in the y direction

Displacement in x direction is not a concern here since we are talking about the gravitational force

the gives you delta y
then use you formula for potential energy due to y displacement to get change on gravitaitonal potential energy I think it is force* delta y * mass

mgy = gravitational potential energy

The force in this case is 9.8 (that due to gravity)