A box is moved from the floor to a tabletop but gains no speed in the process. Is there work done on the box, and if so what has happened to the energy added to the system?
2007-02-20 05:01:41 · 2 answers · asked by damon h 1 in Science & Mathematics ➔ Physics
Damon h,
Because the box was moved in vertical axe, thare is a gravity accelaration remember? So W=F.h; where W=work, F=force and h=height, but F=m.a , where m=masse(in kg) or in your example, you have F=m.g, g=acceleration of gravity.
So, W=m.g.h, and this is the formulae of potential energy!
What do you think about? Is There work?
About the energy added to system:
What happens if you to let the box to go from tabletop to floor? Do you need to push the box to floor? or it goes alone? If it goes alone, some energy there was but now is free,dissipated...and work and energy are the same thing.
I hope to have helped you.
***.Ricardo Souza, Sao Paulo, Brazil.
2007-02-20 12:29:49 · answer #1 · answered by Ricardo Souza, São Paulo, Brazil 2 · 0⤊ 0⤋
Well, if the box gained no speed, then it follows that it by definition did not move. Speed is just distance over time, so if speed is always zero, then distance must have been zero.
Therefore the 'floor' changed to a 'tabletop' by some magic. No work was done on the box because work is defined as mass times distance. Since the distance was zero, then work was also zero.
2007-02-20 05:09:34 · answer #2 · answered by tony1athome 5 · 1⤊ 0⤋