| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.95 |
| Score | 0% | 59% |
Force of friction due to kinetic friction is __________ the force of friction due to static friction.
higher than |
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the same as |
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lower than |
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opposite |
The formula for force of friction (Ff) is the same whether kinetic or static friction applies: Ff = μFN. To distinguish between kinetic and static friction, μk and μs are often used in place of μ.
The mechanical advantage of a block and tackle is equal to which of the following?
the number of loads |
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the number of input forces |
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the number of connecting ropes |
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the number of pulleys |
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.
A wedge is most similar to what other type of simple machine?
second-class lever |
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inclined plane |
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third-class lever |
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first-class lever |
The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.
What's the first gear in a gear train called?
input gear |
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idler gear |
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driven gear |
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driver gear |
A gear train is two or more gears linked together. Gear trains are designed to increase or reduce the speed or torque outpout of a rotating system or change the direction of its output. The first gear in the chain is called the driver and the last gear in the chain the driven gear with the gears between them called idler gears.
Two gears are connected and the smaller gear drives the larger gear. The speed of rotation will __________ and the torque will __________.
decrease, increase |
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increase, increase |
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increase, decrease |
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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.