Question

A metal bob is tied to one of an inextensible string of negligible mass and is rotated in a vertical circle of radius 8m. If the speed of the sphere at the highest point of the circle is 80 m s-1 . Calculate its speed at the lowest point of the circle (g= 10ms-2)

Answer 1

Given:

r = 8m

$\displaystyle V_h$ = 80 m/s

g= 10 m$\displaystyle s^{-2$

To find:

$\displaystyle V_l$ =?

Explanation:

The speed of the sphere at the lowest point of the circle is $\sqrt{5rg}$

∴ V = $\sqrt{5rg}$

     = $\sqrt{5 \times 8\times 10}$

     $\sqrt{400}$

V = $\displaysyle \mathbf{ 200}$  m$\displaystyle \mathbf {s^{-2}}$