| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.09 |
| Score | 0% | 62% |
A fixed pulley is useful for which of the following?
multiplying the input distance |
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changing the direction of the output force |
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changing the direction of the input force |
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multiplying the input 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.
| 30 lbs. | |
| 10 lbs. | |
| 5 lbs. | |
| 0 lbs. |
To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:
Rada = Rbdb
where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.Solving for Ra, our missing value, and plugging in our variables yields:
Ra = \( \frac{R_bd_b}{d_a} \) = \( \frac{60 lbs. \times 1 ft.}{6 ft.} \) = \( \frac{60 ft⋅lb}{6 ft.} \) = 10 lbs.
An inclined plane increases ___________ to reduce ____________.
distance, force |
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distance, power |
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force, distance |
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force, power |
An inclined plane is a simple machine that reduces the force needed to raise an object to a certain height. Work equals force x distance and, by increasing the distance that the object travels, an inclined plane reduces the force necessary to raise it to a particular height. In this case, the mechanical advantage is to make the task easier. An example of an inclined plane is a ramp.
| 1440 ft⋅lb | |
| 120 ft⋅lb | |
| 360 ft⋅lb | |
| 4 ft⋅lb |
Two gears are connected and the smaller gear drives the larger gear. The speed of rotation will __________ and the torque will __________.
increase, decrease |
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increase, increase |
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decrease, increase |
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decrease, decrease |
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.