| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.38 |
| Score | 0% | 68% |
Which of the following is not a type of bridge?
block |
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truss |
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cable |
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arch |
The six basic bridge forms are beam, truss, arch, cantilever, cable, and suspension.
Two or more pulleys used together are called:
third-class lever |
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gears |
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wheel and axle |
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block and tackle |
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.
Which of these will have the most impact on the kinetic energy of an object?
its direction |
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its weight |
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its speed |
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its mass |
Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.
| 1 | |
| 3.3 | |
| 3 | |
| 5 |
The mechanical advantage (MA) of a wedge is its length divided by its thickness:
MA = \( \frac{l}{t} \) = \( \frac{12 in.}{4 in.} \) = 3
Two gears are connected and the smaller gear drives the larger gear. The speed of rotation will __________ and the torque will __________.
increase, increase |
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decrease, 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.