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Physics · PYQ NEET UG 2018
हिन्दीA body initially at rest and sliding along a frictionless track from a height h (as shown in the figure) just completes a vertical circle of diameter \( AB = D \). The height h is equal to
Correct answer · Option 4
\( \frac{5}{4}D \)
Explanation
By conservation of mechanical energy, \( mgh = \frac{1}{2}mv^2 \), where \( v \) is the velocity required at the lowest point of the vertical loop to just complete it, \( v = \sqrt{5gR} = \sqrt{\frac{5gD}{2}} \). Thus, \( mgh = \frac{1}{2}m (\frac{5gD}{2}) \implies h = \frac{5}{4}D \).
