Register to reply

Change in gravitional potential energy at an angle?

by flemj
Tags: angle, energy, gravitional, potential
Share this thread:
flemj
#1
Nov4-08, 02:39 PM
P: 6
1. The problem statement, all variables and given/known data

A 0.23kg pendulum bob is attached to a string 1.2 long at an angle of 30 degrees. What is the change in the gravitational potential energy of the system as the bob swings from point A to point B
U=
2. Relevant equations

.5 mv^2 = mgl
U=E+K


3. The attempt at a solution

in the picture it looks like a string attached to a roof with the ball at rest touching the roof and swinging down to a position 35 degrees below im just not sure how you use the angle of 35 in the problem
Phys.Org News Partner Science news on Phys.org
Sapphire talk enlivens guesswork over iPhone 6
Geneticists offer clues to better rice, tomato crops
UConn makes 3-D copies of antique instrument parts
Hootenanny
#2
Nov4-08, 02:42 PM
Emeritus
Sci Advisor
PF Gold
Hootenanny's Avatar
P: 9,781
Can you relate the change in angle to the change in height of the bob?
flemj
#3
Nov4-08, 02:45 PM
P: 6
Quote Quote by Hootenanny View Post
Can you relate the change in angle to the change in height of the bob?
the height isnt given its just the length of the string sorry.

Hootenanny
#4
Nov4-08, 02:46 PM
Emeritus
Sci Advisor
PF Gold
Hootenanny's Avatar
P: 9,781
Change in gravitional potential energy at an angle?

Quote Quote by flemj View Post
the height isnt given its just the length of the string sorry.
I know it isn't given, what I was saying is can you work it out using the angle and the length of the string?
flemj
#5
Nov4-08, 02:51 PM
P: 6
Quote Quote by Hootenanny View Post
I know it isn't given, what I was saying is can you work it out using the angle and the length of the string?
would you do that my x sin theta ?

im just really frustrated with this question
Hootenanny
#6
Nov4-08, 02:55 PM
Emeritus
Sci Advisor
PF Gold
Hootenanny's Avatar
P: 9,781
Quote Quote by flemj View Post
would you do that my x sin theta ?
I'm not sure what my is meant to be, but yes you should use trigonometry.


Register to reply

Related Discussions
Potential energy of a pendulum when the angle is small Introductory Physics Homework 13
Change in gravitational Potential energy Introductory Physics Homework 9
Gravitional Potential Energy Question Introductory Physics Homework 3
Change potential energy without doing work? General Physics 1
Potential Energy Change Introductory Physics Homework 3