A boat of mass 90 kg is floating in still wat | vedclass

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Question

(B) Since there is no external horizontal force acting on the system (boat + boy),the center of mass of the system remains stationary.Let $M = 90\ kg$

Vedclass · Accepted Answer

$0.75$

Vedclass · Answer

(B) Since there is no external horizontal force acting on the system (boat + boy),the center of mass of the system remains stationary.Let $M = 90\ kg$ be the mass of the boat and $m = 30\ kg$ be the mass of the boy.Let $L = 3\ m$ be the length of the boat.Let $d$ be the distance the boat moves in the opposite direction to the boy.When the boy moves a distance $L$ relative to the boat,his displacement relative to the water is $(L - d)$.The displacement of the boat relative to the water is $-d$.Using the center of mass conservation principle: $m(L - d) + M(-d) = 0$.$30(3 - d) - 90d = 0$.$90 - 30d - 90d = 0$.$90 = 120d$.$d = \frac{90}{120} = 0.75\ m$.

$A$ boat of mass $90\ kg$ is floating in still water. $A$ boy of mass $30\ kg$ walks from the stern to the bow. The length of the boat is $3\ m$. The distance through which the boat moves is .......... $m$.

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