Work = Mass * Gravity * Height and is measured in Joules. Imagine you find a 2 -Kg book 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.
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Work |
= |
M |
* |
G |
* |
H |
|
|
= |
2 |
* |
9.8 |
* |
0.75 |
|
|
= |
14.7 |
Joules |
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If you lift 100 kg of mass 1-meter,
you will have done 980 Joules of work. 
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Work |
= |
M |
* |
G |
* |
H |
|
|
= |
100 |
* |
9.8 |
* |
1 |
|
|
= |
980 |
Joules |
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|
|
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While the book sits on the table, no work is being done because no object is moving, even though forces are involved. 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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Work |
= |
M |
* |
G |
* |
H |
|
|
= |
2 |
* |
9.8 |
* |
0 |
|
|
= |
0 |
Joules |
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Which of the following will result in more work? Running straight up hill, or taking a zigzag path up the hill? The work will be the same for both paths. The direct path requires more force, but less distance, while the zigzag path requires less force but more distance. |
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Work = Mass * Gravity * Height The equation above shows how to calculate the work done. As you can see, your work will be the same – no matter which path you take - because your mass doesn’t change during the trip. Gravity doesn’t change. The final height is the same. Therefore, work is the same. |
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Imagine you open a door by pushing near the hinges. Now imagine you open the same door by pushing near the handle. Which will result in more work? Again, the work done is the same. As you push the door near the hinges, the force needed to move it is greater, but the distance traveled is less. Pushing near the handle, the force is less, but the distance traveled is greater. |
Another Equation for Calculating
Work:
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One can calculate the work done by an airplane by using the equation: W = F x D For instance, if a model airplane exerts 0.25 |
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|
W |
= F x D |
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|
= 0.25 * 10 |
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= 2.5 Joules |
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If you apply a force over a given distance - you have done work. In general, the energy transferred depends on the amount of force and the distance over which that force is exerted. If the object doesn't move, you have not done work, even though you may have expended a great deal of energy! Oh well. |
