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As the drawing illustrates, two disks with masses m1 and m2 are moving horizonta

ID: 2101875 • Letter: A

Question

As the drawing illustrates, two disks with masses m1 and m2 are moving horizontally to the right at a speed of v0. They are on an airhockey table, which supports them with an essentially frictionless cushion of air. They move as a unit, with a compressed spring between them, which has a negligible mass. Then the spring is released and allowed to push the disks outward. Consider the situation where disk 1 comes to a momentary halt shortly after the spring is released. Assuming that m1 = 1.5 kg, m2 = 2.4 kg, and v0 = +5.7 m/s, find the velocity of disk 2 at that moment.

Explanation / Answer

Given data Mass of disk 1 is, m1 =1.5 kg Mass of disk 2 is, m2 = 2.4 kg The disks move with an initial speed, v0 = 5.7 m/s Let the final velocity of disk 2 be v Solution: By using law of conservation of linear momentum, we get the final velocity of disk 2                          (m1 + m2 ) v0 = m2 v     (1.5 kg + 2.4 kg) (5.7 m/s) = (2.4 kg) v                                                v = 9.26 m/s     (1.5 kg + 2.4 kg) (5.7 m/s) = (2.4 kg) v                                                v = 9.26 m/s