View Single Post
nhmllr
#1
Dec16-12, 05:59 PM
P: 184
Okay, let's say I'm holding a wooden block. I then raise it above my head, then lower it to it's original position.

Neither the kinetic or gravitational potential energy of the block has changed, so I have done no work on the block. However, I expended chemical energy to perform this action. Where does that energy go? Into the block?

For example, if I shook a bottle of water up and down really fast then brought it back to its original position, the water will still be moving around, so wouldn't I have done work on it because I've put kinetic energy into the water in the bottle? Would I have done less work if I raised it and lowered it slowly, causing little movement in the water?

Or is the water example fundamentally different from the block example?
Phys.Org News Partner Physics news on Phys.org
First in-situ images of void collapse in explosives
The first supercomputer simulations of 'spin?orbit' forces between neutrons and protons in an atomic nucleus
Magnets for fusion energy: A revolutionary manufacturing method developed