A man weighing $80\, kg$ is standing in a trolley weighing $320 \,kg$. The trolley is resting on frictionless horizontal rails. If the man starts walking on the trolley with a speed of $1 \,m / s$, then after $4\, sec$ his displacement relative to the ground will be ........ $m$
A man weighing $80\, kg$ is standing in a trolley weighing $320 \,kg$. The trolley is resting on frictionless horizontal rails. If the man starts walking on the trolley with a speed of $1 \,m / s$, then after $4\, sec$ his displacement relative to the ground will be ........ $m$
$5$
$4.8$
$3.2$
$3.0$
A man weighing $80\, kg$ is standing in a trolley weighing $320 \,kg$. The trolley is resting on frictionless horizontal rails. If the man starts walking on the trolley with a speed of $1 \,m / s$, then after $4\, sec$ his displacement relative to the ground will be ........ $m$
If the man starts walking on the trolley in the forward direction then whole system will move in backward direction with same momentum.
Momentum of man in forward direction = Momentum of system (man + trolley) in backward direction
$⇒$ $80 \times 1 = (80 + 320) \times v$ $⇒$ $v = 0.2\;m/s$
So the velocity of man w.r.t. ground $1.0 - 0.2 = 0.8\;m/s$
$\therefore $ Displacement of man w.r.t. ground $ = 0.8 \times 4 = 3.2\;m$
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