Question

Which of the following possesses kinetic energy?
(A) A moving car.
(B) A compressed spring
(C) Water stored in the reservoir of a dam
(D) A car parked in the garage.

Answer 1

Hint: The kinetic energy is associated with the motion of the object, if any object is moving it means it has kinetic energy but if it is static it has zero kinetic energy.

Complete step by step answer:
We have to find which of the following options possesses kinetic energy.
We know that kinetic energy is associated with the motion of the object, if any object is moving it means it has kinetic energy but if it is static it means it has zero kinetic energy.
In option A we have a moving car, we know that a moving object possesses kinetic energy, it means this moving car also has kinetic energy. So, option A is correct.
In option B we have a compressed spring, as the compressed spring is static, and it is compressed it means it has stored potential energy which is equal to \[\dfrac{1}{2}k{x^2}\]. Here the kinetic energy is zero at this moment as the spring is static.
In option C we have water stored in the reservoir of a dam, so here the water is static and it has stored potential energy equals mgh. Here kinetic energy is zero.
In option D we have a car parked in the garage, so, we know that the parked car has zero velocity it means it is static. In this case both kinetic and potential energy of the parked car is zero.

Additional information:
Please Note: that the potential energy of an object occurs due to the virtue of object position in static, whereas the kinetic energy of an object occurs due to the virtue of object motion, it means the moving object possesses’ kinetic energy by its motion.

Therefore, option A is correct.

Note:
One may confuse in option B that when the spring has potential energy as well as kinetic energy, we have compressed the spring it means spring has covered some distance let say x it means it has kinetic energy, but actually, this kinetic energy is converted into potential energy of the spring because currently, it is static. Please Note: that kinetic energy is only associated with moving objects.