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Bullet and Pendulum

  • Thread starter BMWPower06
  • Start date
1. The problem statement, all variables and given/known data
An 16.2 g rifle bullet traveling 240 m/s buries itself in a 3.54 kg pendulum hanging on a 2.90 m long string, which makes the pendulum swing upward in an arc. Determine the horizontal component of the pendulum's displacement.


2. Relevant equations

I used the Y center of mass equation which is:
Ycm= m1y1+m2y2/m1+m2 but i got 2.9


3. The attempt at a solution
Im stuck and dont know what else to do
 

malawi_glenn

Science Advisor
Homework Helper
4,782
22
use conservation of (total) energy and momentum. Neglect the heat that the bullet will "create" when hitting the pendelum. You must use some trigometry also.
 

Doc Al

Mentor
44,746
1,031
Consider the interaction as having two stages:
(1) The collision of bullet and pendulum--what's conserved?
(2) The rise of the pendulum+bullet (post collision)--what's conserved?
 
Consider the interaction as having two stages:
(1) The collision of bullet and pendulum--what's conserved?
(2) The rise of the pendulum+bullet (post collision)--what's conserved?
so i find the PE+KE=PE+KE for both parts

or in other words

.5MV2=mgh for both parts?
 

malawi_glenn

Science Advisor
Homework Helper
4,782
22
Yes.

First the energy is the kinetic energy of bullet. Then all energy will be potential energy of the pendelum and the bullet. (m1+m2)gh
 

Doc Al

Mentor
44,746
1,031
so i find the PE+KE=PE+KE for both parts

or in other words

.5MV2=mgh for both parts?
Not exactly. Different quantities are conserved in each part of the motion. For example: During the collision, mechanical energy is not conserved. What is?
 

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