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bobie
Gold Member
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Edit: Suppose you are pulling a weight along a track at an angle (in the picture 45°).
horse pulling a cart on a track
If the object is dislocated by a distance D let's assume that the work done/energy tranmitted to the object is $E_{45}$ = K J. If you had pulled along the track, would the distance covered by the object be $D_0$ = K/cos45° and $E_0$ = K/cos45 = 1.41 * K? if this is correct, can we conclude that the energy wasted/ calories burned doing no mechanical work is 41 %?.
(If this is not correct, how can we calculate the energy wasted when we apply a force at an angle greater than 0°?)
I know that no mechanical work in excess is done, that is because of the peculiarity of the definition of work. I tried to dodge this ostacle speaking of *calories burned*: I thought we can desume that by reverse engineering.
The logic is this: we have instruments (I am referring to instruments, so we avoid inefficiency of human muscles) to produce and measure force. If we measure the force something exerts on a blocked object, then remove the block and measure the oucome of that force, can't we deduce that the same force has been applied before and the **same amount of energy/calories has been wasted?**
If this logic is valid, the same logic has been applied to the horse.
A biologist can tell us the percentage of calories burned in excess of the effective force applied/ transmitted, the inefficiency of the human machine is around 80%: you burn 4 - 5 times more energy than you put to avail. Efficiency may vary from 18% to 26%. In the case above energy actually burned would be 41*4.5 = ca. 185%
horse pulling a cart on a track
If the object is dislocated by a distance D let's assume that the work done/energy tranmitted to the object is $E_{45}$ = K J. If you had pulled along the track, would the distance covered by the object be $D_0$ = K/cos45° and $E_0$ = K/cos45 = 1.41 * K? if this is correct, can we conclude that the energy wasted/ calories burned doing no mechanical work is 41 %?.
(If this is not correct, how can we calculate the energy wasted when we apply a force at an angle greater than 0°?)
I know that no mechanical work in excess is done, that is because of the peculiarity of the definition of work. I tried to dodge this ostacle speaking of *calories burned*: I thought we can desume that by reverse engineering.
The logic is this: we have instruments (I am referring to instruments, so we avoid inefficiency of human muscles) to produce and measure force. If we measure the force something exerts on a blocked object, then remove the block and measure the oucome of that force, can't we deduce that the same force has been applied before and the **same amount of energy/calories has been wasted?**
If this logic is valid, the same logic has been applied to the horse.
A biologist can tell us the percentage of calories burned in excess of the effective force applied/ transmitted, the inefficiency of the human machine is around 80%: you burn 4 - 5 times more energy than you put to avail. Efficiency may vary from 18% to 26%. In the case above energy actually burned would be 41*4.5 = ca. 185%
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