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Energy is defined as the ability to do work. If you can measure how much work an object does, or how much heat is exchanged, you can determine the amount of energy that is in a system. Read this for more information. As with energy, work is also measured in Joules.
Calculating Work
Calculating Work
One can calculate the work by using the equation:
Work = Force x Distance
Force is measured in Newtons. Distance is measured in meters. You should see that the work done in all three ramp is the same. This is because the vertical displacement is the same.
Link to more work information.
Work = Mass * Gravity * Height
Work = Mass * Gravity * Height
It is easy to calculate the work done when lifting something.
Imagine you find a 2 -Kg box on the floor and lift it 0.75 meters and put it on a table. Remember, that “force” is simply a push or a pull.
Work = MGH
= 100 * 9.8 * 0.75
= 735 Joules
Doing Work
Doing Work
If energy or gravitational potential energy changes, then work is done.
The force can act in the same direction of motion. Or, the force can act against the motion. (Drag and friction do that.) Forces can act when objects touch.
In general, the energy transferred depends on the amount of force and the distance over which that force is exerted.
If the man pushes the rock in the direction of the force, he has done work. If the rock rolls back and pushes him, then the rock does work on the man.
No work
No work
If the net force is perpendicular to the motion then no work is done. If you push on an object and it doesn’t move, then no work is done. If an object’s kinetic energy doesn’t change, then no work is done.
While reading a book, no work is being done because no object is moving.
If a force (like gravity) is applied to an object (like the book) but it does not move, no work has been done.
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