Which one among the following happens when a swing rises to a certain height from its rest position ?
[amp_mcq option1=”Its potential energy decreases while kinetic energy increases” option2=”Its kinetic energy decreases while potential energy increases” option3=”Both potential and kinetic energy decrease” option4=”Both potential and kinetic energy increase” correct=”option2″]
This question was previously asked in
UPSC NDA-1 – 2015
At the rest position (lowest point), the swing has its maximum speed and thus maximum kinetic energy (assuming negligible energy loss). As it rises, its height above the lowest point increases, causing its gravitational potential energy (PE = mgh) to increase. Simultaneously, the swing slows down as it moves upwards against gravity, causing its kinetic energy (KE = 1/2 mv^2) to decrease.