Register to reply

Collisions problem (How should I approach it)

by Hindi
Tags: collisions
Share this thread:
Hindi
#1
Dec13-03, 08:22 PM
P: 9
Hi all,

I came across a problem on collisions on one of my professors old exams. The problem is:

http://home.comcast.net/~msharma15/problem_2.jpg

The way I am trying to approach it is by applying the conservation of linear momentum and energy, but the problem is that I still get left with 3 unknowns.

Here is what I know:
Before the collision, only block A has kinetic energy.

After the collision, the K.E. of system is (1/2 K.E. initial). block A has -1/2MV^2 and block B has 1/2MV^2.

The final collision is what confuses me. Should I just work with K.E.i (only block A moving) with conservation of linear momentum?

Any help would be greatly appreciated. Thanks!
Phys.Org News Partner Science news on Phys.org
New type of solar concentrator desn't block the view
Researchers demonstrate ultra low-field nuclear magnetic resonance using Earth's magnetic field
Asian inventions dominate energy storage systems
StephenPrivitera
#2
Dec13-03, 08:58 PM
P: 364
by cons of p,
[tex]m_1v_{1i}=m_1v_{1f}-m_2v_{2f}[/tex]
where v_2f is reckoned as negative
By the energy conditions,
[tex]m_1v_{1i}^2=\frac {1}{2}(m_1v_{1f}^2+m_2v_{2f}^2)[/tex]
which gives two equations with two unknowns.
Hindi
#3
Dec13-03, 09:51 PM
P: 9
Thanks for the reply
StephenPrivitera. I am just wondering why you made m_2v_2f negative in the first equation?? Should it be the other way around?

Doc Al
#4
Dec14-03, 10:39 AM
Mentor
Doc Al's Avatar
P: 41,436
Collisions problem (How should I approach it)

The equations should be:
[tex]m_1v_{1i}=-m_1v_{1f}+m_2v_{2f}[/tex]
[tex]\frac {1}{4}m_1v_{1i}^2=\frac {1}{2}(m_1v_{1f}^2+m_2v_{2f}^2)[/tex]
(where the speeds are all positive)


Register to reply

Related Discussions
Closest approach of particle problem - Please help Introductory Physics Homework 12
Not sure how to approach problem Introductory Physics Homework 55
Unsure how to approach problem General Math 0
How to approach this problem Calculus 1
Pendulum problem using Lagrangian approach Introductory Physics Homework 6