If you lift a 10lb weight it is considerd doing work, but
if you walk a mile with that same weight is it considerd the same type
of work? If so, what is the difference between the two?
Work is force times distance. It makes no difference in what direction.
you lift the object farther above the ground, you have added potential
of position). If you move the object horizontally, you have still done
have added no potential energy.
In the case of lifting the object, because you have stored energy (defined
ability to do work) you could use it to do work. Just let it go and it
Force times distance...
The energy of position is sometimes called GPE - gravitational potential
This differentiates it from potential energy such as chemical potential energy.
work = force times distance
joules = newtons times meters (at least in the metric system)
Do you know what a "slug" is? It is a unit of measure you might want to
It's not the same. In the first case, you're moving something against a
opposing force. The work done is the force you're exerting multiplied by
the weight moves while you're exerting the force.
In the second case the only work done is in getting the weight from a
walking speed (I'll assume you're walking in a straight line at constant
speed -- i.e.,
no accelerations). Ideally, once you have the weight moving you just let
It feels like work to you, because muscles use energy just to maintain
the work is not being done on the weight.
Click here to return to the Physics Archives
Update: June 2012