11is it rite?
A trolley of mass 200kg moves with a uniform speed of 36km/h on a frictionless track.A child of mass 20kg runs on the trolley from one end to the other ,10m away,with a speed of 4 m/s relative to the trolley in a direction opposite to its motion,and jumps out of the trolley.What is the final speed of the trolley?How much has the trolley moved from the time the child begins to run??
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2 Answers
11Conservation of momentum
200*10 + 20*4 = 200*v
2000 + 80 = 200v
2080 = 200v
v = 10.4 m/s
Total time = 10/4 = 2.5sec
S = 2.5*10
S = 25m
