a coolie with a load of 30kg on his head, walks on the platform. if he walks a distance of 60m what is the work done by the coolie?

how much energy is gained by a box of mass 20kg when a man runs carrying the box with a speed of 3m/s to catch the bus?

what is the difference in the answers in these two questions? is the meaning the same, please explain.

Asked by saibaba1069 | 2nd Apr, 2021, 08:40: PM

Expert Answer:

If speed is constant and not varying  , walking with constant speed and running with constant speed gives same effect.
If the coolie walks with 30 kg load on a horizontal platform , there is no workdone to move the 30 kg load in gravitational field.
Work is done on 30 kg load in gravitational field only if the 30 kg load is moved vertically.
Only workdone by the coolie is , he should be able to withstand the 30 kg load on his head and is effort of body to walk with load.
Similarly if a man runs at 3 m/s by carrying a 20 kg box , box is not gaining energy .
Only the man has to put some additional effort to run with the box . If the man stops suddenly the box will not fly with 3 m/s speed.

Answered by Thiyagarajan K | 2nd Apr, 2021, 09:57: PM