(a) Which two physical quantities are necessary for measurement of work done? and (b) Find the work done by a porter in lifting a luggage of 20 kg from ground on his head. (Given, height of porter, s =1.7 m, acceleration due to gravity, g = 10 m/s2). Also find out the work done by gravity on the luggage.
A worker lifts a load to a building of height ‘h’ by applying force in the same direction displacing the load under gravity.(a) In which direction does the force of gravity acts?, (b) Which one of these forces is doing positive work? Give reason., (c) Which one of these forces is doing negative work? Give reason.