Linear momentum conservation vs mecanical energy conservation

  • Thread starter jaumzaum
  • Start date
  • #1
392
23
A ball A (mass ma) with initial velocity v colides with a ball B (mb) initially stopped. A and B gets the same direction/velocity v', Calculate v'

By linear momentum conservation
ma.v = (ma + mb).v'
v' = mav(ma + mb)

But by mecanical energy conservation

ma.v²/2 = (ma + mb).v'²/2
v' = v (ma/(ma + mb))^(1/2), which is wrong

Why we can't use mecanical energy conservation, is there a energy dissipation?
 

Answers and Replies

  • #2
olivermsun
Science Advisor
1,248
118
A ball A (mass ma) with initial velocity v colides with a ball B (mb) initially stopped. A and B gets the same direction/velocity v', Calculate v'
...
Why we can't use mecanical energy conservation, is there a energy dissipation?

Well, for A and B to get the same direction/velocity v' after the collision, don't they have to stick?

Does that sound like an elastic collision?
 

Related Threads on Linear momentum conservation vs mecanical energy conservation

Replies
2
Views
6K
Replies
7
Views
4K
Replies
5
Views
3K
Replies
5
Views
2K
Replies
9
Views
4K
  • Last Post
Replies
8
Views
3K
  • Last Post
Replies
4
Views
1K
  • Last Post
Replies
12
Views
2K
Replies
3
Views
766
  • Last Post
Replies
2
Views
710
M
Top