• Support PF! Buy your school textbooks, materials and every day products Here!

2D elastic collision help please

  • #1

Homework Statement


The attached file is all the information on the problem

Homework Equations


.5mv^2 =.5mv1^2 + .5m2^2
p = mv

The Attempt at a Solution


I've tried plugging the known values in the equations and and substituting the various equations together and every time I come up with an equation that has two unknowns in it.
 

Attachments

Answers and Replies

  • #2
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
8,586
2,031
Did you write down three (3) equations? Two for momentum conservation and one for energy conservation.
 
  • #3
Did you write down three (3) equations? Two for momentum conservation and one for energy conservation.
yes I did, the equations I was able to come up with are:
V1cos(θ1) + V2cos(θ2) = 5 (momentum in x direction)
V1sin(θ1) + V2sin(θ2) = 0 (momentum in y direction)
.5(V1)2 + .5(V2)2 = 12.5 (energy conservation)
θ1 + θ2 = 90

I worked on these equations for about an hour and came up with nothing, and feel like there is something i'm missing
 
Last edited:
  • #4
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
8,586
2,031
Sorry, I cannot read the fine print. Can you make all characters the same size?
 
  • #5
Sorry, I cannot read the fine print. Can you make all characters the same size?
Had a problem with subscripts overlapping but I think it's fixed.
 
  • #6
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
8,586
2,031
You are missing that sinθ1 = cosθ2 and cosθ1 = sinθ2. You should be able to get either one of these angles from the geometry of the collision.
 

Related Threads for: 2D elastic collision help please

Replies
4
Views
430
  • Last Post
Replies
2
Views
7K
  • Last Post
Replies
5
Views
768
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
4
Views
648
  • Last Post
Replies
4
Views
464
  • Last Post
Replies
7
Views
2K
  • Last Post
Replies
9
Views
3K
Top