| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.28 |
| Score | 0% | 66% |
An inclined plane increases ___________ to reduce ____________.
force, power |
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force, distance |
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distance, power |
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distance, force |
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.
If the handles of a wheelbarrow are 3 ft. from the wheel axle, what force must you exert to lift the handles if it's carrying a 270 lb. load concentrated at a point 0.5 ft. from the axle?
0.83 lbs |
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90 lbs |
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810 lbs |
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45 lbs |
This problem describes a second-class lever and, for a second class lever, 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 3 ft. = 270 lbs x 0.5 ft
Fe = 135 ft-lb. / 3 ft
Fe = 45 lbs
The mechanical advantage of a wheel and axle is equal to the:
ratio of the diameters of the wheels |
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length of the axle |
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difference in the lengths of the axles |
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difference in the diameters of the wheels |
A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.
An object's resistance to changes in direction is known as:
inertia |
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kinetic energy |
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mass |
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weight |
The more mass a substance has the more force is required to move it or to change its direction. This resistance to changes in direction is known as inertia.
According to Boyle's law, for a fixed amount of gas kept at a fixed temperature, which of the following are inversely proportional?
pressure, volume |
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volume, mass |
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density, volume |
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pressure, density |
Boyle's law states that "for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional".