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Physics · PYQ NEET UG 2019(1)
हिन्दीBody A of mass 4m moving with speed u collides with another body B of mass 2m, at rest. The collision is head on and elastic in nature. After the collision the fraction of energy lost by the colliding body A is:
Correct answer · Option 4
\( \frac{8}{9} \)
Explanation
Final velocity of body A after elastic collision is \( v_1 = \frac{m_1 - m_2}{m_1 + m_2}u = \frac{4m - 2m}{4m + 2m}u = \frac{1}{3}u \). Fraction of energy lost = \( \frac{\frac{1}{2}m_1u^2 - \frac{1}{2}m_1v_1^2}{\frac{1}{2}m_1u^2} = 1 - (\frac{1}{3})^2 = \frac{8}{9} \).
