Finding the Post-Collision Velocity: Is My Calculation Correct?

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Homework Help Overview

The problem involves a collision scenario where Daisy, a skater, collides with her friend who is stationary. The objective is to determine the post-collision velocity of both individuals moving together after the collision, using principles of conservation of momentum.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants discuss the application of the conservation of momentum formula, questioning the correctness of calculations and the proper use of multiplication versus addition in the context of the equation.

Discussion Status

Multiple attempts at calculation have been presented, with some participants providing corrections and clarifications regarding the formula and arithmetic involved. There appears to be a productive exchange of ideas, though no consensus on the final answer has been reached.

Contextual Notes

Participants are operating under the constraints of homework rules, which may limit the extent of guidance provided. There is an emphasis on ensuring correct application of the formula and arithmetic operations.

Mowgli
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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
 
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using the equation

m1v1 + m2v2 = (m1 + m2)vf

I think you forgot to multiply the speed of Daisy to her mass.
 
Mowgli said:

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.
 
Mowgli said:

Homework Equations



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

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

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