The minimum velocity required to complete a full circle in a vertical plane is given to a bob of mass m suspended by a string of length 25 cm. When it reaches the highest point, it collides elastically with another bob of mass m suspended by a string of length `l_(2),` which is initially at rest. After the collision, if the second bob acquires the minimum speed required to complete a full circle in the vertical plane, then the length of the string `l _(2)` __m. (Both the strings are massless and in-extensible)

Answer

`00.05`

Explanation

To complete the vertical circle using principle of conservation of linear oment , `sqrt ( gl _(1)) = sqrt ( 5 gl _(2))`
`( l _(1))/( l_(2)) = 5`
`therefore l _(2) = (25)/(5) = 5 cm = 0.05m`