Question

A boy and a cart are moving in the same direction, with the boy going twice as fast as the cart. When he

gets into the cart, the speed of the cart increases by 20%. Find the ratio of mass of cart to mass of boy

A) 5 B) 4 C) 3 D) 2 pls give explanation along with the answer

Answer 1

Concept:-There are no external forces in this case,so, momentum will be conserved......

,

Now,let the mass of the man be m and that of cart be M

let the velocity of cart be v then velocity of man will be 2v

initial momentum=Mv+2mv

final speed of cart together with man=v+20percent of v=6v/5

final momentum=(M+m)×6v/5

initial momentum=final momentum

Mv+2mv=(6v/5)×(M+m)

M+2m=6/5 (M+m)

5M+10m=6M+6m

-M=-4m

M/m=4

Hence the ration of mass of cart to man is 4