Question

A particle of mass 100g is thrown vertically upwards with a speed of 5m/s. The work done by the force of gravity during the time the particle goes up is ___________

(a) 1.25J

(b) 0.5J

(c) -0.5J

(d) -1.25J

This question was posed to me in exam.

The origin of the question is Work Done topic in chapter Kinematics of Engineering Physics I

Answer 1

The correct option is (d) -1.25J

The explanation: Work done by the force of gravity = Loss in kinetic energy of the body

Work done by the force of gravity = 1/2 m(v^2-u^2) = 1/2×100/1000×(0^2-5^2)J

Work done by the force of gravity = -1.25J.