| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.29 |
| Score | 0% | 66% |
Connected gears of different numbers of teeth are used together to change which of the following charasteristics of the input force?
energy |
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rotational direction |
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force |
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torque |
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.
Normal force is generally equal to the __________ of an object.
coefficient of friction |
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mass |
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weight |
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density |
Normal force arises on a flat horizontal surface in response to an object's weight pressing it down. Consequently, normal force is generally equal to the object's weight.
Which of the following statements about drag is false?
slower objects experience more drag than faster objects |
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the amount of drag depends on the speed of an object |
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the amount of drag depends on the shape of an object |
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drag occurs during movement through a fluid |
Drag is friction that opposes movement through a fluid like liquid or air. The amount of drag depends on the shape and speed of the object with slower objects experiencing less drag than faster objects and more aerodynamic objects experiencing less drag than those with a large leading surface area.
Hydraulics is the transmission of force through the use of which of the following?
air pressure |
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gear systems |
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torque |
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liquids |
Hydraulics is the transmission of force through the use of liquids. Liquids are especially suited for transferring force in complex machines because they compress very little and can occupy very small spaces. Hydraulic pressure is calculated by dividing force by the area over which it is applied: P = F/A where F is force in pounds, A is area in square inches, and the resulting pressure is in pounds per square inch (psi).
Two or more pulleys used together are called:
wheel and axle |
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block and tackle |
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gears |
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third-class lever |
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.