| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.51 |
| Score | 0% | 70% |
The standard unit of energy is the:
Joule |
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Horsepower |
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Watt |
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Volt |
The Joule (J) is the standard unit of energy and has the unit \({kg \times m^2} \over s^2\).
| 1.9 | |
| 3.3 | |
| 1.3 | |
| 0.6 |
The gear ratio (Vr) of a gear train is the product of the gear ratios between the pairs of meshed gears. Let N represent the number of teeth for each gear:
Vr = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) \( \frac{N_3}{N_4} \) ... \( \frac{N_n}{N_{n+1}} \)
In this problem, we have only two gears so the equation becomes:Vr = \( \frac{N_1}{N_2} \) = \( \frac{20}{16} \) = 1.3
The mechanical advantage of connected gears is proportional to which characteristic of the gears?
diameter |
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circumference |
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number of teeth |
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speed |
The mechanical advantage (amount of change in speed or torque) of connected gears is proportional to the number of teeth each gear has. Called gear ratio, it's the ratio of the number of teeth on the larger gear to the number of teeth on the smaller gear. For example, a gear with 12 teeth connected to a gear with 9 teeth would have a gear ratio of 4:3.
Which of the following is not a type of bridge?
arch |
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block |
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cable |
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truss |
The six basic bridge forms are beam, truss, arch, cantilever, cable, and suspension.
For any given surface, the coefficient of static friction is ___________ the coefficient of kinetic friction.
lower than |
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equal to |
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opposite |
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higher than |
For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).