Change in momentum after hitting a wall

AI Thread Summary
The discussion revolves around calculating the change in momentum when a 1.0 kg ball traveling at 4.0 m/s strikes a wall and bounces back at 2.0 m/s. The correct answer for the change in momentum is determined to be 6 kg m/s, corresponding to option C. The user initially miscalculated the change in momentum as 2 kg m/s, not accounting for the direction of the velocities. The importance of considering the sign associated with velocity in momentum calculations is emphasized. This highlights a common error in physics problems involving momentum and direction.
gake
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Homework Statement



32) The change in momentum, in kg m/s, that occurs when a 1.0 kg ball traveling at 4.0 m/s strikes a wall
and bounces back at 2.0 m/s is
A) 2.
B) 4.
C) 6.
D) 8.
Answer: C

Homework Equations



Momentum==Mass*Velocity

The Attempt at a Solution



I get A.

Momentum1==1*4
Momentum2==1*2

Momentum1-Momentum2==2
 
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Consider the "sign" associated with the two velocities.
 
What a dumb mistake! Thanks :)
 
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