Question

A body is suspended from a smooth horizontal nail by a string of length $0.25$ metre. What minimum horizontal velocity should be given to it in the lowest position so that it may move in a complete vertical circle with the nail at the centre?

• A. $\sqrt{12.25}\,ms^{-1}$
• B. $4.9\,ms^{-1}$
• C. $7\sqrt{2}\,ms^{-1}$
• D. $\sqrt{9.8}\,ms^{-1}$

Answer 1

Answer: (A)

$\sqrt{12.25}\,ms^{-1}$

Answer 2

When a string fixed with a nail, moves along a vertical circle, then the minimum horizontal velocity at the lowest point of circle is given by $v =\sqrt{5 rg }=\sqrt{5 \times 0.25 \times 9.8}$ $=\sqrt{12.25} m / s$