Answer:
Option D
Explanation:
Work is done when an object displaces from its initial position on the application force.
In option A, the car rolls down without the application of force and hence it is not correct.
In option B , Turbine is standing still and hence again there is no force or displacement which could lead to work. Hence, it is also incorrect
In option C, the internal molecules of balloon starts moving after gaining heat energy but there is no displacement of balloon overall and hence the work done is zero.
However, in option D work is done in pedaling the cycle. The number of revolutions of the cycle is counted which is cal-liberated and converted into distance in kilometers. Hence, it is correct
