| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.41 |
| Score | 0% | 68% |
The steering wheel of a car is an example of which type of simple machine?
block and tackle |
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wheel and axle |
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first-class lever |
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fixed pulley |
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.
A shovel is an example of which class of lever?
second |
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a shovel is not a lever |
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third |
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first |
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.
Collinear forces:
act along the same line of action |
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are unrelated to each other |
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act in a common plane |
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pass through a common point |
Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.
Two gears are connected and the larger gear drives the smaller gear. The speed of rotation will __________ and the torque will __________.
decrease, decrease |
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increase, increase |
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decrease, increase |
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increase, 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.
What defines the mechanical advantage of a first class lever?
output force |
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output distance |
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input force |
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position of the fulcrum |
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.