Two pendulums C and D suspended from a wire as shown in the figure given below. Pendulum C is made to oscillate by displacing it from its mean position. It is seen that D also starts oscillating.

(i) Name the type of oscillation, C will execute.
(ii) Name the type of oscillation, D will execute.
(iii) If the length of D is made equal to C then what difference will you notice in the oscillations of D?
(iv) What is the name of the phenomenon when the length of D is made equal to C?

Explanation

(i) C will execute free or natural oscillations.
(ii) D will execute forced oscillations.
(iii) The amplitude of oscillations of D will increase and it will oscillate is same phase as that of C.
(iv) Resonance.