Correct Answer – C
(c ) When a pendulum oscillates in air, it will lose energy continuously in overcoming resistance due to air. Therefore, total mechanical energy of the pendulum decreases continously with time.
The variation is correctly represented by curve (c ).

Correct Answer – C
When a pendulum is oscillating in air, its total mechanical energy decreases exponentially with time. Hence, option (c) represents correct diagram.

(c ) When a pendulum oscillates in air, it will lose energy continously in overcoming resistance due to air. Therefore total mechanical energy of the pendulum decreases continously wity time. The variation is correctly represented by curve(c ).