0
$\begingroup$

I read this question in the textbook, "Concepts of Physics, Vol. 1":

"When you lift a box from the floor and put it on an almirah the potential energy of the box increases, but there is no change in its kinetic energy. Is it a violation of conservation of energy?"

The answer ofcourse would be no but how I am not sure?

I first thought that it would have taken energy from something else thus keeping the total energy constant but then realised that this argument was rubbish as I could not think of anything that lost energy.

The potential energy here is given by $$U = -mgh$$ h increases and U must be constant so g must decrease and it does decrease. But the decrease is minuscule and I have a feeling that even this line of reasoning is wrong.

So how to resolve this seeming paradox?

Improve this question
$\endgroup$

1 Answer 1

Reset to default
4
$\begingroup$

When you lift a box from the floor and put it on an almirah the potential energy of the box increases, but there is no change in its kinetic energy. Is it a violation of conservation of energy?

I could not think of anything that lost energy

You lost energy.

Improve this answer
$\endgroup$
2
  • $\begingroup$ So the earlier reasoning was not rubbish indeed. $\endgroup$
    – Prasoon Jha
    Commented Aug 30, 2023 at 15:26
  • $\begingroup$ @Laplace'sDemon yes. The reasoning is not rubbish $\endgroup$
    – Dale
    Commented Aug 30, 2023 at 16:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.