Finding initial speed of 'Porsche' using inelastic collision with reference frame

  • Thread starter 7skk
  • Start date
  • #1
1
0

Homework Statement


blah blah blah

Homework Equations


momentum = momentum'
mv + mv = (m1+m2)v
(Uk)N = friction force


The Attempt at a Solution



It's hard to find how to start with randomly given values.
Thank you so much for your help! :D
 
Last edited:

Answers and Replies

  • #2
Delphi51
Homework Helper
3,407
11
It is a 2D problem so you must write two headings for North/South and East/West. Then write that "momentum before = momentum after". Follow that up with an "mv" for each moving object in each part. Then put in your numbers. If you are still having trouble, show us your work and someone will be pleased to pitch in and help!
 
  • #3
Delphi51
Homework Helper
3,407
11
No, I don't think any of it makes sense. Even the
1380kg v + 2304kg v = 3684kg v
can't be right because before the collision you don't have two vehicles moving in either the north/south or east/west direction. Got to write the two headings and two separate equations!

You do have to find the speed of the pair of them after the collision from the friction and distance information given. That is an ordinary 1D accelerated motion problem, a little complicated because there is no time info. Do you have the accelerated motion formula with v's, d and a but no t? That is perfect for the job. If you don't have it you could derive it by solving Vf = Vi + at for t and subbing into
d = Vi*t+.5*a*t^2. Or you could sketch the v vs t graph and use the fact that the area under the graph is the distance.
 

Related Threads on Finding initial speed of 'Porsche' using inelastic collision with reference frame

Replies
4
Views
1K
  • Last Post
Replies
3
Views
3K
Replies
1
Views
2K
Replies
2
Views
4K
Replies
5
Views
11K
Replies
4
Views
611
  • Last Post
Replies
5
Views
7K
  • Last Post
Replies
1
Views
5K
Replies
1
Views
1K
Top