Which of the diagrams shown in figure, represents variation of total mechanical energy of a pendulum oscillating in air as function of time ?

Which of the diagrams shown in figure, represents variation of total m

1.	Which of the diagrams shown in figure, represents variation of total mechanical energy of a pendulum oscillating in air as function of time ?
Answer» Solution :When a pendulum oscillates in air, it LOSES energy continuously in overcoming RESISTANCE due to air,Therefore, total mechanical energy of the pendulum decreases continuously with TIME. The variation of total mechanical energy `E` with time `t` is shown CORRECTLY by curve (c).