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Consider the two children in the situation above, who push on each other as they

ID: 1260147 • Letter: C

Question

Consider the two children in the situation above, who push on each other as they fight. If the push lasts for 0.50 s, what is the magnitude of the average force exerted by the larger child on the smaller one?

A) 25 N B) 112 N C) 70 N D) Zero

Two angry children are fighting while standing on a very slippery icy surface (see figure). Their masses are m1 = 25 kg and m2 = 40 kg, and they are initially at rest. The larger child pushes the smaller child, who then slides away to the left with a speed of 1.4 m/s. Consider the two children in the situation above, who push on each other as they fight. If the push lasts for 0.50 s, what is the magnitude of the average force exerted by the larger child on the smaller one? A) 25 N B) 112 N C) 70 N D) Zero

Explanation / Answer

momentum transfer :

0 = 25*1.4 - 40*v

v = .875

Net momentum transfer = 25*1.4 = 35

Force = 35/.5 = 70 N