A small sphere `B` of mass `m` is released form rest in the position shown and swings freely in a vertical plane, first about `O` and then about the peg `A` after the cord comes in contact with the peg. Determime the tension in the cord

(a) just before the sphere comes in contact with the peg.
(b) just after it comes in contact with the peg.

Answer

A, B, C, D

Explanation

`h=0.8sin30^(@)=0.4m`
:. `v^(2)=2gh`
(a) just before,
`T_(1)-mgsin30^(@)=(mv^(2))/(R_(1))` , `(R_(1)=0.8m)`
`T_(1)=(mg)/(2)+(m(2g)(0.4))/(0.8)`
`=(3mg)/(2)`
(b) just after,
`T_(2)-mgsin30^(@)=(mv^(2))/(R_(2))` , `(R_(2)=0.4m)`
`T_(2)=(mg)/(2)+(m(2g)(0.4))/(0.4)`
or `T_(2)=(5mg)/(2)`