Objectives
- Students will use observation skills to reach conclusions and make observations
- Students will learn about force and work.
Materials
- Pencil
- Two large coins
- Ruler
- Journal
Procedure
- Start with a mini lesson about work. Here is some basic information:
By definition, work is the result of a force moving an object over some distance. Pushing against a wall may use a lot of force, but if the wall doesn't move, no work is done.
On the other hand, when you turn the pages of a book, work is being done. Your finger applies force to each page, moving it over a distance. The amount of work is small, but work is being done.
Scientifically speaking, "work" and "force" (or effort) are two different things. Work is the result of a force (a push or a pull) moving an object over some distance.
Force X Distance = Work
Look at the equation. If force and distance are small, like when you're turning the pages in a book, then work is small. What would happen if the distance were zero? No work would be done, no matter how much force was applied. Pushing against a wall may use a lot of force, but unless the wall actually moves, no work is being done.
There are a lot of simple machines, like levers, pulleys, and ramps, that make it so that you don't need to use as much force to do the same amount of work. How do they do this? Well, they increase the distance over which the work is done. Did you ever sit on a see-saw with an adult much heavier than you? You know that there is no way you could lift the adult using just your arms. But by sitting on the very end of the see-saw, you are able to lift a person much heavier than yourself. The see-saw is a lever that helps you do the work by spreading the force you apply over a greater distance.
Instructions for the Project:
- Place the pencil under the middle of the ruler and put a coin on one end.
- Drop the second coin from a height of about one foot so it hits the other end of the ruler at about the three inch mark. Observe what happens. Write your observations in your journal.
- Next, from the same height, drop the second coin again at the very end of the ruler.
- Notice that the closer to the end of the ruler the dropped coin falls, the higher the other coin jumps. The greater the distance, the more force is exerted.
