A boy of mass m climbs up a stairs of vertical height h.

(a) What is the work done by the boy against the force of gravity?

(b) What would have been the work done if he uses a lift in climbing the same vertical height?

What physical quantity does electron volt (eV) measure? How is it related to the S.I. unit of that quantity?

Name the physical quantity which is measured in calorie. How is it related to the S.I unit of that quantity?

(a) Name the physical quantity measured in terms of horsepower.

(b) How is horsepower related to the S. I. unit of power?