| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.95 |
| Score | 0% | 59% |
The force amplification achieved by using a tool, mechanical device or machine system is called:
work |
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efficiency |
|
power |
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mechanical advantage |
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Such a device utilizes input force and trades off forces against movement to amplify and/or change its direction.
Which of the following is not true of a first-class lever?
changes the direction of force |
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increases distance |
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decreases distance |
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increases force |
A first-class lever is used to increase force or distance while changing the direction of the force. The lever pivots on a fulcrum and, when a force is applied to the lever at one side of the fulcrum, the other end moves in the opposite direction. The position of the fulcrum also defines the mechanical advantage of the lever. If the fulcrum is closer to the force being applied, the load can be moved a greater distance at the expense of requiring a greater input force. If the fulcrum is closer to the load, less force is required but the force must be applied over a longer distance. An example of a first-class lever is a seesaw / teeter-totter.
| 322.5 lbs. | |
| 358.3 lbs. | |
| 360.3 lbs. | |
| 361.3 lbs. |
This problem describes an inclined plane and, for an inclined plane, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance:
Fede = Frdr
Plugging in the variables from this problem yields:
Fe x 6 ft. = 430 lbs. x 5 ft.
Fe = \( \frac{2150 ft⋅lb}{6 ft.} \) = 358.3 lbs.
Which of the following will increase the mechanical advantage of this inclined plane?
lower the force acting at the blue arrow |
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shorten the ramp |
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increase the force acting at the blue arrow |
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lengthen the ramp |
The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In order to increase mechanical advantage, this ratio must increase which means making the effort distance longer and this can be accomplished by lengthening the length of the ramp.
| 108 | |
| 59 | |
| 270 | |
| 300 |