A body P of mass 3 kg at rest is dropped from a height of 250 m. At the same moment another body Q of mass 2 kg is thrown vertically upwards with velocity $50\text{ m s}^{-1}$. Both move along same line. The velocity of Q when centre of mass reaches maximum height is: (g = $10\text{ m s}^{-2}$)}
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At COM extremum, use weighted velocity condition $m_1v_1+m_2v_2=0$.