Conservation of Energy: Pushing Boxes

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SUMMARY

The discussion centers on the conservation of energy when pushing boxes of different sizes across a surface. When pushing a medium-sized box, energy is transferred to the box, resulting in kinetic energy, while some energy is dissipated as thermal energy due to friction. In contrast, when pushing a larger box against a frictional force that cannot be overcome, no work is done on the box, and the energy expended is dissipated as thermal energy within the body. This leads to the conclusion that pushing against an immovable object generates more heat in the body than pushing an object that moves.

PREREQUISITES
  • Understanding of basic physics concepts, particularly work and energy transfer.
  • Familiarity with friction and its effects on motion.
  • Knowledge of thermal energy and its relation to mechanical work.
  • Basic principles of kinetic energy and potential energy.
NEXT STEPS
  • Research the laws of thermodynamics and their application to mechanical systems.
  • Explore the concept of work done against friction in physics.
  • Study the relationship between energy expenditure and heat generation in physical activities.
  • Investigate practical experiments demonstrating energy conservation in various scenarios.
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Students of physics, educators teaching energy concepts, fitness enthusiasts analyzing energy expenditure, and anyone interested in the practical applications of mechanical work and energy conservation.

PowerWill500
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I have a question regarding the conservation of energy. If I were to push a medium sized box across a surface, I would be imparting a certain amount of energy to it (and myself) and also dissipating a certain amount of thermal energy into the surface. This energy I'm supplying comes from the transfer of the chemically stored energy in my body when I push the box, yes?

Now, if I were to expend an equal amount of bodily energy pushing against a large box, and was not able to overcome the friction force, would all that energy be instead dissipated as thermal energy into the ground and box? Maybe I'm just overestimating the awesomeness of kinetic energy, but intuition (often wrong, admittedly) tells me that the thermal energy produced in the second scenario would not be equivalent to the kinetic and thermal energy my efforts produced in the first. Apologies for a potentially dumb question, but could someone explain this?
 
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Yes indeed, you transfer energy to ground (in both cases).
In fact u cannot push a box against a wall if the wall is not well connected to the ground.

Ll.
 
No. In the second case, since you did not overcome friction, no work was done on the box and whatever (food/chemical) energy was merely dissipated as thermal energy within your body.
 
cesiumfrog said:
No. In the second case, since you did not overcome friction, no work was done on the box and whatever (food/chemical) energy was merely dissipated as thermal energy within your body.

But if that's the case, I would get hotter pushing something that didn't move than pushing something that did, even if I was expending the same amount of energy. That doesn't make sense to me.
 
PowerWill500 said:
But if that's the case, I would get hotter pushing something that didn't move than pushing something that did, even if I was expending the same amount of energy. That doesn't make sense to me.
Why not? Try it! You will most certainly get hotter if you push hard on an immovable wall for more than a few seconds.
 

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