Momentum and Impulse. find final velocity

AI Thread Summary
In an elastic collision problem, a 0.10-kg object moving at 0.20 m/s collides with a stationary 0.15-kg object. The initial attempt to use the combined mass formula was incorrect, as it only applies when objects stick together post-collision. Instead, the conservation of momentum and kinetic energy must be applied separately to find the final velocities of both objects. The correct approach involves using the equations m1v1i + m2v2i = m1v1f + m2v2f and the conservation of energy. The final velocity of the 0.10-kg object is determined to be -0.045 m/s after applying these principles.
maxjohnfresh
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Homework Statement


A 0.10-kg object moving initially with a velocity of 0.20 m/s eastward makes an elastic head-on collision with a 0.15-kg object initially at rest. What is the final velocity of the .10 kg object after the collision ?


Homework Equations



im not sure which equation to use :/

The Attempt at a Solution



i tried using m1v1+m2v2=(m1+m2) V
but it didnt come out right.

and i know the answer is -0.045 m/s
 
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Hi maxjohnfresh, welcome to PF.
i tried using m1v1+m2v2=(m1+m2) V
This formula is true if both objects move together after collision.
So use the formula
m1v1i+m2v2i=(m1v1f+m2v2f) .
Apply the conservation of energy and solve for v1f and v2f.
 

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