Perfectly elastic collision


by southernbelle
Tags: collision, elastic, perfectly
southernbelle
southernbelle is offline
#1
Dec3-08, 08:11 AM
P: 35
1. The problem statement, all variables and given/known data
In an isolated system, cart1 (with mass = 1 kg and vi1 = 2) has a perfectly elastic collision with cart2 (with mass = 2 kg and vi2 = 0). Find the velocity of cart1 and the velocity of cart2 after the collision.
I have to solve this using kinetic energy and momentum equations.


2. Relevant equations
m1vi1 + m2vi2 = m1v1f + m2v2f
1/2m1vi12 + 1/2m2vi22 = 1/2m1v1f2 + 1/2m2v2f2


3. The attempt at a solution
I have gotten to this point:
2= V1F + 2V2F
4= V1F2 + 2V2F

but I cannot get the numbers to work out correctly.
Using another equation I know that V1f = 2/3 and V2f = 4/3

I am doing substitution wrong or something.
Please help!!
Phys.Org News Partner Science news on Phys.org
SensaBubble: It's a bubble, but not as we know it (w/ video)
The hemihelix: Scientists discover a new shape using rubber bands (w/ video)
Microbes provide insights into evolution of human language
Doc Al
Doc Al is offline
#2
Dec3-08, 08:17 AM
Mentor
Doc Al's Avatar
P: 40,905
Quote Quote by southernbelle View Post
3. The attempt at a solution
I have gotten to this point:
2= V1F + 2V2F
This makes sense.
4= V1F2 + 2V2F
How did you get this?
southernbelle
southernbelle is offline
#3
Dec3-08, 11:16 AM
P: 35
I got that by solving the kinetic energy equation.
I mutiplied both sides by 2 to get rid of the halves.

It is actually supposed to read:

4 = Vif^2 + 2V2f^2

Doc Al
Doc Al is offline
#4
Dec3-08, 12:01 PM
Mentor
Doc Al's Avatar
P: 40,905

Perfectly elastic collision


Quote Quote by southernbelle View Post
It is actually supposed to read:

4 = Vif^2 + 2V2f^2
That's good.

Take the first equation and solve for one of your variables. Then substitute that into the second equation. Solve the quadratic.


Register to reply

Related Discussions
Perfectly elastic collision Introductory Physics Homework 2
perfectly elastic collision Introductory Physics Homework 3
Perfectly Elastic Collision Problem Introductory Physics Homework 15
[SOLVED] Perfectly Elastic Collision Introductory Physics Homework 5
perfectly elastic collision Introductory Physics Homework 7