A girl of mass 50, kg jumps out of a moving boat of mass 300, kg on to bank with a horizontal veloci

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7. MOTION

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A girl of mass $50\, kg$ jumps out of a moving boat of mass $300\, kg$ on to the bank with a horizontal velocity of $3\, m s ^{-1}$. With, what velocity, does the boat begin to move backwards ?

Option A

Option B

Option C

Option D

Solution

Here, $m_{1}=50 kg , m_{2}=300 kg$

$v_{1}=3 m s ^{-1}$

$v_{2}=?$

$m_{1} v_{1}+m_{2} v_{2}=0$

$50 \times 3+300 \times v_{2}=0$

$300 v_{2}=-150$

$v_{2}=-\frac{150}{300}$

$=-0.5 m s ^{-1}$

Negative sign is for backward motion of the boat

Standard 9

Science

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