A block of mass 2 kg 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 = 40 N. The kinetic energy of the particle increases 40 J in a given interval of time. Then, `(g = 10 m//s^(2))`

Options

A. Tension in the string is 40 N
B. Displacement of the block in the given interval of time is 2m
C. Workdone by gravity is –20 J
D. Workdone by tension is 80 J

Answer

A, B, D

Explanation

`F = "net force" = T - mg = 40 - 2 (10) = 20 N , " "Fs = Delta K implies s = 40/20 = 2m`
W (by gravity) = - mgs = -40 J, " "W (by T) = Ts = 80 J`.