A body initially at rest sliding along a frictionaless 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

A body initially at rest sliding along a frictionaless track from a he

1.	A body initially at rest sliding along a frictionaless 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
Answer» `3/2 D` `D` `7/5 D` `5/4 D` SOLUTION : As body is at rest INITIALLY, i.e., SPEED = 0 At point A, speed = v, As track is frictionless , so TOTAL mechanical energy will remain constant `:. (T.M.E)_(i) = (T.M.E)_f` `0 mgh = 1/2 mv^2 + 0 " or " h= (v^2)/(2g)` For completing the vertical circle, `v ge sqrt(5 gR)` `:. h = (5 gR)/(2g) = 5/2 R = 5/4 D`