Work is the most obvious form of energy. For example, lifting a weight involves work. In fact, we can measure the amount of work done lifting a weight if we know how much the weight weighs and through what distance it has been raised. To be technical about it, this is a form of mechanical work.
One way to define work in general is to say that:
Work is any process that ultimately results in a weight being raised or lowered.We can measure such work using the formula
where m is the mass being lifted (or dropped), g is the acceleration of gravity, and h is the change in vertical distance involved. The minus sign is there because of a thermodynamic convention that we'll talk about later.
Example: A 1.50 kg weight is raised 3.2 meters. How much work is done?
The appropriate value of g is 9.80665 m/sec2. Multiplying these gives a value of -47 Joules for the work done.
Previous: 4.4 Heat and Work Up: 4.4 Heat and Work Next: 4.4.2 Heat Paul J. Gans
2003-02-19
