You lift a suitcase from the floor and keep it on a table. The work done by you on the suitcase does not depend on
a) the path taken by the suitcase
b) the time taken by you in doing so
c) the weight of the suitcase
d) your weight
Our system consists of the suit case and the earth. work done by you = change in K.E. of the system + change in P.E. of the system. Now, change in K.E of earth = 0 change in K.E. of the suitcase = 0, change in P.E. of the system = mgh where m = mass of the suitcase, h = height of table. Since gravitational force is a conservative force, work done does not depend upon path. Also work done does not depend upon the weight of the person who is doing work. Time determines the average power delivered by the person but the work done is independent of the time.
6th Floor, NCC Building, Durgamma Cheruvu Road, Vittal Rao Nagar, HITEC City, Hyderabad, Telangana 500081.
