# Homework Help: Pendulum Physics problem

1. Nov 24, 2008

### BugsSport

1. The problem statement, all variables and given/known data
I have to calculate the speed of a bullet, based on the amount of displacement created when the bullet becomes lodged in the log.
I have the horizontal displacement, the weight of the log, and the length of the string.

2. Relevant equations
I'm not sure how to set this up so I don't know what equations to use yet.

3. The attempt at a solution
I calculated the horizontal displacement and have enough information to finish the problem, but I'm not sure which equations to use. Any start is appreciated, thanks.

2. Nov 24, 2008

### LowlyPion

KE = PE

The ½mV² of the bullet becomes the mgh of the log displacement.

You know L and θ apparently so ...

3. Nov 24, 2008

### BugsSport

I just figured it out. Thanks for the response though

4. Nov 24, 2008

### BugsSport

Just for future reference, this page helps a lot in pendulum problems
http://www.rowan.edu/colleges/lasold/PhysicsAndAstronomy/LabManual/labs/EnergyInAPendulum.pdf [Broken]

Last edited by a moderator: May 3, 2017