Question

A boy of mass 60 kg is running at 5m/s. Find work done by him

Answer 1

as distance= 1/2 × mass × (velocity)square

therefore, s = 1/2m(v)square
s =1/2 × 60 × 5 × 5
s = 750 m

as work done= distance × force
W= s × f
W = s × mass × gravitational force
W = s × m × g
W = 750 × 60 × 9.8
W=441000

hope you understand well...☺☺☺☺

Answer 2

Mass = 60 kg

Velocity = 5m/s

kinetic energy = 1/2 m v^2

                        = 1/2 (60)(5)^2

                        = 1/2 (60)(25)

                         =750J

Hence the wok done by a boy is 750 J.