| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.85 |
| Score | 0% | 57% |
| 2.0 | |
| 10 | |
| 5 | |
| -5 |
The mechanical advantage of a wheel and axle is the input radius divided by the output radius:
MA = \( \frac{r_i}{r_o} \)
In this case, the input radius (where the effort force is being applied) is 10 and the output radius (where the resistance is being applied) is 5 for a mechanical advantage of \( \frac{10}{5} \) = 2.0
Two or more pulleys used together are called:
third-class lever |
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wheel and axle |
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gears |
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block and tackle |
Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement. So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.
Normal force is generally equal to the __________ of an object.
density |
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weight |
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mass |
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coefficient of friction |
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.
The advantage of using a third-class lever is that it increases:
the force applied to the load |
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the speed of the load |
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the mechanical advantage of the lever |
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the distance traveled by the load |
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.
Two gears are connected and the larger gear drives the smaller gear. The speed of rotation will __________ and the torque will __________.
decrease, increase |
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increase, decrease |
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decrease, decrease |
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increase, increase |
Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.