A simple pendulum consists of a 50 cm long string connected to a 100 g ball. The ball is pulled aside so that the string makes an angel of `37^0` with the vertical and is then released. Find the tension in the string when the bob is at its lowest position.

Answer

A, D

Explanation

From the figure

`costheta=(AC)/(AB)`
`rarr AC=Abcostheta`
`=(0.5)xx(0.8)=0.4`
`So, CD=(0.5)-(0.4)`
`=)(0.1)m`
Energy at D=energy at B`
`1/2 mv^2=mg(CD)`
`v^2=2xx10x(0.1)=2`
`So, the tension is given by
`T=(mv^2)/r+mg`
`(0.1)(2/0.5+10)=1.4N`