question_answer 69)

                  Two pendulums with identical bobs and lengths are suspended from a common support such that in rest position the two bobs are in contact (Fig.). One of the bobs is released after being displaced by 10' so that it collides elastically head-on with the other bob.                 (a) Describe the motion of two bobs.                 (b) Draw a graph showing variation in energy of either pendulum with time, for \[0\,\le \,t\le \,2T,\]where T is the period of each pendulum.                

Answer:

                  (a) When one bob say A is released from its displaced position, it collides with another bob B and transfer its entire momentum to the another ball B. The bob A comes to rest and the bob B is displaced by \[{{10}^{o}}\]. The bob B rises to a certain height and then comes back to its initial position. At this stage it transfer all of its momentum to bob A and then comes to rest. But die bob A is displaced by \[{{10}^{o}}\]. This process continues.