why does a man carrrying load to rest feel tired after sometime even though he hasn't done any work?
Answers
Answer:
would give you a similar example. So, try to push/pull a wall (or anything which is too heavy for you to move). As expected, it will not move and no work will be done. After this exercise, do you feel tired?
The answer is yes, because you applied force. It didn't get your work done but you did put some physical energy into it, right?
This loss of energy makes you feel tired.
Now, when we lift some weight and stand, what exactly are we doing?
The earth's gravitational force is trying to pull that weight towards it (proportional to the mass of that object). When we are lifting an object we have to apply a force in the opposite direction with a magnitude that is higher than that gravitational pull; and to keep it lifted in a constant position you have to apply the same amount of force as the gravitational pull does.
So, it seems like you do have to put some effort here. Shouldn't you be tired?