A block of mass M is hanging over a smooth and light pulley through a light string. The other end of the string is pulled by a constant force F. The kinetic energy of the block increases by 20 J in 1s.
(A) The tension in the string is Mg
(B) The tension in the string is F
(C) The work done by the tension on the block is 20 J in the above 1s
(D) The work done by the force of gravity is –20 J in the above 1s
