Collision with an unknown mass and velocity after

  • Thread starter fantisism
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  • #1
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Homework Statement


You slide a 2 kg block on a flat icy surface towards a static block of mass M. Before the collision, the 2 kg mass is moving at 3 m/s. The total kinetic energy is not changed by the collision. After the collision, the 2 kg mass is moving at −1 m/s i.e. opposite to its original direction. Calculate the mass M in kg and the velocity of the mass M after the collision.

Homework Equations


Eq 1.) 0.5mv1i2+0.5Mv2i2=0.5mv1f2+0.5Mv2f2
Eq 2.) mv1i+Mv2i=mv1f+Mv2f

The Attempt at a Solution


I got v2f=2 m/s and M=4 kg. I solved for M for the second equation and substituted that in into the first equation.
 

Answers and Replies

  • #2
ehild
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Homework Statement


You slide a 2 kg block on a flat icy surface towards a static block of mass M. Before the collision, the 2 kg mass is moving at 3 m/s. The total kinetic energy is not changed by the collision. After the collision, the 2 kg mass is moving at −1 m/s i.e. opposite to its original direction. Calculate the mass M in kg and the velocity of the mass M after the collision.

Homework Equations


Eq 1.) 0.5mv1i2+0.5Mv2i2=0.5mv1f2+0.5Mv2f2
Eq 2.) mv1i+Mv2i=mv1f+Mv2f

The Attempt at a Solution


I got v2f=2 m/s and M=4 kg. I solved for M for the second equation and substituted that in into the first equation.
What is your question then? That result is correct.
 
  • #3
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What is your question then? That result is correct.
Oh sorry. I just wanted to make sure those were right because I tend to make small simple math errors. Thank you!
 
  • #4
ehild
Homework Helper
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You are welcome:oldsmile:
 

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