Work and the Human Body Lab 2
Inclined Planes / Name ______
Date ______
Essential Questions
1. What is the relationship between force and motion?
2. What does it look like when we do work? / Vocabulary
work, force, energy, inclined plane, simple machine, Newton, joule / Objectives
1. Explain and investigate work, energy and force.
2. Contrast situations where work is done with different amounts of force to situations where no work is done.
The inclined plane is a simple machine. It helps us do work by decreasing the force that we have to use to move an object through a vertical distance. There has to be a trade off, though, so we have to apply that smaller force for a longer distance. For example, if you lift a 20-N object through a height of 5 meters, you have done 100 J of work. The inclined plane might only require us to apply a force of 10-N to move the same object to the same height but we would have to apply that force through a distance of 10 meters (m). We are still doing 100 J of work (10-N x 10-m=100 J) but we are exerting a smaller force over a longer distance.
Some historians think that the pyramids in Egypt were built this way. The blocks of stone are huge and very heavy. The workers may have built giant ramps of dirt to lessen the force that they would have to apply to lift the stones into place. They would have had to exert that force over a longer distance, however.
Materials:
Lab Modified from: M. Poarch – 2003
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Wooden ramps
Books
Spring scales
Meter Sticks
Lab Modified from: M. Poarch – 2003
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Remember that Work = Force x Distance.
PURPOSE/PROBLEM: Compare the way that force and distance change relative to each other in different inclined plane situations.
Imagine that your goal is to lift a textbook the height of four textbooks. In other words, the work that you are to do involves lifting a textbook the height of four textbooks, as shown below:
Pre-Lab Question:
What could be used to help you lift the book using less force?
Procedure:
You will set up four different inclined planes to help you do the work of lifting the book to the height pictured on page 1. ALWAYS USE FOUR BOOKS IN SETTING UP YOUR INCLINED PLANE. CHANGE THE ANGLE OR STEEPNESS OF THE INCLINED PLANE BY MOVING THE BOOKS FARTHER UNDER THE RAMP.
1. The distance of the ramps will be as follows
A: ______B: ______C: ______D: ______
Data Collection: Set up each of the 4 ramps. Set up the book and spring scale as your teacher shows, and apply just enough force with the spring scale to start moving the book up the ramp.
Distance (m) / Force (N) / Work (J)A. / X / =
B. / X / =
C. / X / =
D. / X / =
Conclusion and Analysis
1. If we take away the impact of friction, the same amount of work was done with and without the use of the ramp. Why is the inclined plane helpful?
2. When we moved the books over a greater distance what happened to the force needed to move them?
a. Longer distance equals less force needed
b. Longer distance equals more force needed
c. Longer distance did not affect the force needed
3. Which inclined plane was most helpful and why?
4. Identify some health benefits to using machines to do work.
5. Can you identify another simple machine that makes work easier by increasing distance and reducing force?
Lab Modified from: M. Poarch – 2003
http://science-class.net 2