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Technology: Engineering Our World
In general, heavier objects need longer ramps or more effort to move
them upward: the more gradual the rise, the less effort required. We can say
the length of the inclined plane is directly related to the mass of the object.
This means that as mass increases, ramp length increases. Figure 8-28
shows this relationship. So does the following formula:
Effort (E) × Effort Distance (ED) = Resistance (R) × Resistance Distance (RD)
Now, let us see how we might use the formula to work out a problem.
Suppose, for example, that a mass of 450 lb. (200 kg) needs to be raised
6′ (2 m). Then suppose that the most force that can be exerted is 100 lb.
(50 kg). How long must the ramp be so the force is able to move the object?
ED = R ×
RD
E
450 × = 27´ =
6
100
2700
100
200 × = 8 m =
2
50
400
50
Metric calculation:
U.S. Customary calculation:
Formula:
B
A
gure 8-27. We use inclined
planes for many purposes. A—Skilled
skateboarders use ramps to perform
various feats. B—Ramps provide
access to multistory parking garages.