A pendulum consists of a bob (small metal sphere) attached to the end of a piece of string. The other end of the string is attached to a fixed point. The bob oscillates with small oscillations about its equilibrium position, as shown in the figure below.
The length 
of the pendulum, measured from the fixed point to the centre of the bob, is 
. The acceleration 
of the bob varies with its displacement 
from the equilibrium position as shown in the graph below.
While the pendulum is oscillating, the length of the string is increased in such a way that the total energy of the oscillations remains constant. Suggest and explain the qualitative effect of this change on the amplitude of the oscillations.
