Given below are two statements:
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.

Question

A body of mass 2 kg is moving with a velocity of 3 m/s. What is its kinetic energy?

Answer 1

To solve the given statement-based question, let's analyze each statement individually:

Statement I: A truck and a car moving with the same kinetic energy are brought to rest by applying brakes that provide equal retarding forces. Both come to rest in equal distance.
The statement is correct. Given that both the truck and the car have the same initial kinetic energy and experience the same retarding force, they will come to rest after covering the same distance. According to the work-energy principle, the work done by the braking force (which brings the vehicles to rest) is equal to the initial kinetic energy. Therefore, if both have the same kinetic energy and experience the same braking force, they will stop in the same 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.
The statement is incorrect. When a car changes its direction from east to north while maintaining the same speed, it experiences a change in velocity due to the change in direction. Since velocity is a vector quantity (having both magnitude and direction), a change in direction implies a change in velocity. Hence, there is an acceleration acting on the car, called centripetal acceleration, during the turn, even though its speed remains constant. Therefore, the statement that "the acceleration of the car is zero" is incorrect.

Based on the analysis above:

Thus, the most appropriate answer is: Statement I is correct but Statement II is incorrect.

Answer 2

To solve the given statement-based question, let's analyze each statement individually:

Statement I: A truck and a car moving with the same kinetic energy are brought to rest by applying brakes that provide equal retarding forces. Both come to rest in equal distance.
The statement is correct. Given that both the truck and the car have the same initial kinetic energy and experience the same retarding force, they will come to rest after covering the same distance. According to the work-energy principle, the work done by the braking force (which brings the vehicles to rest) is equal to the initial kinetic energy. Therefore, if both have the same kinetic energy and experience the same braking force, they will stop in the same 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.
The statement is incorrect. When a car changes its direction from east to north while maintaining the same speed, it experiences a change in velocity due to the change in direction. Since velocity is a vector quantity (having both magnitude and direction), a change in direction implies a change in velocity. Hence, there is an acceleration acting on the car, called centripetal acceleration, during the turn, even though its speed remains constant. Therefore, the statement that "the acceleration of the car is zero" is incorrect.

Based on the analysis above:

Thus, the most appropriate answer is: Statement I is correct but Statement II is incorrect.

The Correct Option is C