| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.01 |
| Score | 0% | 60% |
A fixed pulley is useful for which of the following?
multiplying the input distance |
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multiplying the input force |
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changing the direction of the input force |
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changing the direction of the output force |
A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.
Normal force is generally equal to the __________ of an object.
mass |
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coefficient of friction |
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weight |
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density |
Normal force arises on a flat horizontal surface in response to an object's weight pressing it down. Consequently, normal force is generally equal to the object's weight.
Which of the following represents the force a surface exerts when an object presses against it?
friction |
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normal force |
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mass |
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counter force |
Normal force (FN) represents the force a surface exerts when an object presses against it.
| 1 | |
| 6 | |
| 3 | |
| 4.5 |
The mechanical advantage (MA) of a wedge is its length divided by its thickness:
MA = \( \frac{l}{t} \) = \( \frac{6 in.}{2 in.} \) = 3
A shovel is an example of which class of lever?
first |
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second |
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a shovel is not a lever |
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third |
A third-class lever is used to increase distance traveled by an object in the same direction as the force applied. The fulcrum is at one end of the lever, the object at the other, and the force is applied between them. This lever does not impart a mechanical advantage as the effort force must be greater than the load but does impart extra speed to the load. Examples of third-class levers are shovels and tweezers.