Question

which of the following case is work done positive negative or zero a.work done by a Porter has given lifting it from the platform on to his head b.work done by the force of gravity on a suitcase at the suitcase falls down from the porters head c. work done by a person on a book held in his hand while walking with uniform speed on a horizontal Road in briefly

Answer 1

a is negative the porter is lifted upward the workdone by the gravity is negative
b. positive a=+g when the porter fall towrd the earth the workdone by the gravity is positive
c. is zero a=0 when the person is holding the porter thwn no or zero work done by porter
work done

Answer 2

Answer:

in (c) answer is zero

Explanation:

the person is applying force in upward direction by holding it and and moving towards horizontal surface, displacement is horizontal thats means both the things are happening in perpendicular direction or as we know if both are perpendicular to each other then work done will must be zero