Consider the two bobs as shown in the figure. The bobs are connected to the hinges through massless rods. If tA be the time taken by the bob A to reach the lowest position and tB be the time taken by the bob B to reach the lowest position. (Both bobs being released from rest from a horizontal position) then the ratio tAtB is
Consider a situation when the bob A has fallen through an angle 0.
Loss in PE = Gain in KE
⇒12lω2=mgl sin θ
⇒ωA=√2mgl sinθI=√2mgl sinθml2
ωA=√2g sinθl
In the similar position, for B
ωB=√4g sinθl
⇒ωAωB=tAB=√12
⇒tBtA=√2