: Two sprinters leave the starting gate at the same time at the beginning of a s

Question

: Two sprinters leave the starting gate at the same time at the beginning of a straight track. The masses of the two sprinters are 57 kg and 65.5 kg. A)A few seconds later, the first sprinter is ahead of the second by a distance 5.7 m. How far ahead of the second sprinter is the center of mass of these two sprinters, in meters? answer is 2.652 B)If the speeds of the sprinters are 5.4 m/s and 3.1 m/s, respectively, how fast, in meters per second, is the center of mass moving? answer is 4.17 What is the momentum of the center of mass, in kilogram meters per second? I really need help answering this part of the question

Explanation / Answer

(a) let d be the distance ahead of second sprinter where center of mass is

65.5 * d = 57 * (5.7-d) solving we get d=2.652 m

(b) velocity of center of mass = [(57*5.4)+(65.5*3.1)] / (57+65.5) = 4.17 m/s

(c) momentum of the center of mass = total mass * velocity of center of mass = (57+65.5) * 4.17 = 510.83 kg/ms

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