Concept:A swinging pendulum bob has zero kinetic energy at the point of release and at the opposite extreme, but maximum kinetic energy at the centre of the swing.
Explanation:Let
d be the distance moved from the point of release. At
d=0, the bob is momentarily at rest, so its kinetic energy K.E.
=0.
As the bob moves towards the central equilibrium position, its speed increases. Therefore, its K.E. gradually rises to a maximum value at the centre.
After crossing the centre, the bob slows down while moving towards the opposite extreme. Hence its K.E. decreases smoothly and becomes zero again at that extreme.
So the correct graph starts from zero, rises to a peak, and then falls back to zero along a smooth curve.
This shape is represented by graph III.
Answer:Option C (III)
