The bob A of a pendulum released from 30^(@) to the vertical hits another bob B of the same mass at rest on a table as shown in figure . How high does the bobA rise after the collision ? Neglect the size of the bobs and assume the collision to be elastic .

The bob A of a pendulum released from 30^(@) to the vertical hits anot

1.	The bob A of a pendulum released from 30^(@) to the vertical hits another bob B of the same mass at rest on a table as shown in figure . How high does the bobA rise after the collision ? Neglect the size of the bobs and assume the collision to be elastic .
Answer» Solution :When ball A reaches bottom oint its velocity is HORIZONTAL , hence ,we can use law of conservation of linear momentumin the horizontal direction . (a) Two balls have same massand the collisionbetween them iselasti c , therefore , ball A transfers its entire linear momentum to ball B . Hence , BALLA will come to at rest after collision . (b) SPEED with which bob B starts moving = Speed with which bob A hits bob B ` = sqrt(2gh)` `= sqrt(2xx9.8 xx1)` ` = sqrt(19.6)` `= 4.42 ` m/s