Exam-style question
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A 2 kg object moving at 3 m/s collides with a stationary 1 kg object. Assuming an elastic collision, calculate the final velocity of the 2 kg object after the collision.
Model answer
What a good answer should say
- The final velocity of the 2 kg object after the collision is 2 m/s.
Explanation
Why this works
This question tests the application of conservation of momentum in elastic collisions. The formula for conservation of momentum is m1u1 + m2u2 = m1v1 + m2v2.
Substituting the values gives (2 kg * 3 m/s) + (1 kg * 0 m/s) = (2 kg * v1) + (1 kg * v2). Solving the equations leads to the final velocity of the 2 kg object being 2 m/s.
Common mistake
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