Doing some homework with kinetic energy and potential energy. I came across 3 questions that I am struggling with. Basically we have a mass attached to the end of a string. The string is hanging straight down to start off these questions. The following questions assume that the string never has slack in it!
#1, If the length of the string is 1m, calculate the angle made by the string with the vertical when height=.1m?
#2, If the mass is .06kg, what is the tension on the string when height=.1m?
#3, What is the tension of the string when the ball falls back to its original position from a height .1m?
Well, I know mgh=1/2mv2, the m will cancel out leaving us with, gh=1/2v2
The Attempt at a Solution
For #1, If I draw this out, we will have a shape that looks like a right triangle with the hypotenuse of 1m and the vertical side of 1m-height (.1)=.9m. Using SOHCAHTOA we should get an angle of 25.84 degrees.
For #2, I'm not sure about this one, I think I have to label all the forces acting on the mass and do something from there.
For #3,Shouldn't the tension of the string be the Net Force=ma? The only tension acting on the string in the initial position (which is at 0 degrees) should be just the .6kgx9.8?