Question

Which is true about the total mechanical energy of a pendulum in the absence of friction?

Answer 1

Total Mechanical Energy = Potential Energy + Kinetic Energy
Although PE and KE change their sum ME remains constant irrespective of the position of the bob, during the motion of the pendulum.

Answer 2

hmm..without any friction the total sum i.e mechanical energy would still remain same but constant and there would be no losses ..as bob moves to its highest potential its KE gets converted to PE and as it is at its reference position the PE gets converted to max KE or i could say you can see the the bob with it highest VELOCITY it can achieve during its swinging period ..but as i said no losses the pendulum won't stop swinging.. it would move indefinitely until an external force such as friction is appiled..!!
hope this would help ..
correct me if i am wrong..:)