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

Collisions and Impulse

  • Thread starter Mowgli
  • Start date
  • #1
31
0

Homework Statement



Daisy (65.0kg) skates on ice at 4.5m/s to greet her friend (75.0kg), who is standing still, with open arms. As they collide, while holding each other, with what speed do the both move off together?


Homework Equations



MaVa+MbVb / Ma+Mb


The Attempt at a Solution



Is this correct?

(Va+b)=75(0)+(65)(4.5) / 75+65
= 0+69.5 / 140
= .496m/s

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
217
0
using the equation

m1v1 + m2v2 = (m1 + m2)vf

I think you forgot to multiply the speed of Daisy to her mass.
 
  • #3
461
8

The Attempt at a Solution



Is this correct?

(Va+b)=75(0)+(65)(4.5) / 75+65
= 0+69.5 / 140
= .496m/s
(65)(4.5)=/=69.5
Multiplication not addition.
 
  • #4
Doc Al
Mentor
44,874
1,124

Homework Equations



MaVa+MbVb / Ma+Mb
Careful with parentheses. This should be: (MaVa+MbVb) / (Ma+Mb)

Redo your calculation.
 
  • #5
31
0
So I got (75(0) + 65(4.5)) / (75+65)
= 0+292.5 / 140
= 2.1 m/s
 
  • #6
217
0
that's correct :biggrin:
 
  • #7
31
0
thank you so much!
 

Related Threads for: Collisions and Impulse

  • Last Post
Replies
9
Views
8K
  • Last Post
Replies
2
Views
3K
  • Last Post
Replies
6
Views
5K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
24
Views
2K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
12
Views
3K
  • Last Post
Replies
1
Views
454
Top