Sushila goes to a park and rides a swing. When she reaches the highest point, she pauses for a fraction of a second before coming down. At the lowest point she moves the fastest. She keeps swinging without anyone pushing again and again for some time. She does not know the reason.

Answer the following :

(i) Which mechanical energy is maximum at the highest point ?

(ii) Which mechanical energy is maximum at the lowest point ?

(iii) Is mechanical energy generated again when she swings back up ?

(iv) Give one condition when the swing may finally stop with reason.

(v) What information is given by the passage about energy ?

(i) At the highest point, potential energy is maximum because the height of the swing is greatest, while the speed is momentarily zero.

(ii) At the lowest point, kinetic energy is maximum because the speed of the swing is greatest and height is minimum.

(iii) No, mechanical energy is not generated again. It is only converted from kinetic energy to potential energy and from potential energy to kinetic energy during the motion.

(iv) The swing will finally stop due to air resistance and friction at the pivot. These forces gradually dissipate mechanical energy as heat, reducing the motion.

(v) The passage shows that mechanical energy is continuously transformed between potential and kinetic energy and is gradually lost due to external resistive forces.