Engineering Board Exam Reviewer · Engineering Mechanics · hard
A 5 kg ball moving at 7 m/s collides with a 4 kg ball moving at -3 m/s (negative indicating the opposite direction). After the collision, the first ball moves at 2 m/s. Using conservation of momentum, what is the velocity of the second ball after the collision?
- 2
- -3.25
- 2.56
- 3.25
Answer
D. 3.25
Solution
Conservation of momentum: m1v1 + m2v2 = m1v1' + m2v2'. (5)(7) + (4)(-3) = (5)(2) + (4)v2'. Solving, v2' = 3.25 m/s.
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