Two bodies of mass $10 k g$ and $2 k g$ are moving with velocities $2 i - 7 j + 3 k$ and $- 10 i + 35 j - 3 k$ $m / s$ respectively. The velocity of their CM is

2 i

m/s

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2 k

m/s

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(2 i + 2 k)

m/s

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(2 i + 2 j + 2 k)

m/s

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Solution

The correct option is B $2 k$ m/s
$V_{c . m} = \frac{m_{1} v_{1} + m_{2} v_{2}}{m_{1} + m_{2}}$

$V_{c . m} = \frac{10 (2 i - 7 j + 3 k) + 2 (- 10 i + 35 j - 3 k)}{10 + 2}$

$= \frac{20 i - 20 i - 70 j + 70 j + 30 k - 6 k}{12}$

$= \frac{24 k}{12}$

$= 2 k$

The velocity is $2 k$ m/s

Suggest Corrections

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