Statement I: A truck and a car moving with same kinetic energy are brought to rest by applying brakes which provide equal retarding forces. Both come to rest in equal distance.
Statement II : A car moving towards east takes a turn and moves towards north, the speed remains unchanged. The acceleration of the car is zero.
In the light of given statements, choose the most appropriate answer from the options given below.
(A)Statement I is correct but Statement II is incorrect✓ Correct
(B)Statement I is incorrect but Statement II is correct
(C)Both Statement I is correct but Statement II are incorrect
(D)Both Statement I is correct but Statement II are correct
Answer: (A)
Solution
By the work–energy theorem the braking force does work equal to the loss of kinetic energy, so Fs=K, giving s=FK. With the same kinetic energy and the same retarding force, the truck and the car stop in the same distance, so Statement I holds. In the second situation the car keeps a constant speed but changes its direction of motion from east to north; because velocity is a vector, this change of direction means the velocity itself changes, and the car has a non-zero centripetal acceleration during the turn. Therefore Statement II fails. Statement I is correct while Statement II is incorrect.
JEE Main · 2023 · 12 Apr 2023 · Shift 1 · Single correct option
