Question

A body slides down a frictionless track which ends in a circular loop of diameter D, then the minimum height h of the body in term of D so that it may just complete the loop, is

• A. $h = \frac{5D}{2}$
• B. $h = \frac{5D}{4}$
• C. $h = \frac{3D}{4}$
• D. $h = \frac{D}{4}$

Answer 1

Answer: (B)

$h = \frac{5D}{4}$

Answer 2

We know $h = \frac{5}{2}r$ $= \frac{5}{2}\left( \frac{D}{2} \right) = \frac{5D}{4}$ [For critical condition of vertical looping]