| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.44 |
| Score | 0% | 69% |
The mass of an object correlates to the size of the object but ultimately depends on:
the object's density |
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gravity |
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the object's weight |
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the object's potential energy |
Mass is a measure of the amount of matter in an object. In general, larger objects have larger mass than smaller objects but mass ultimately depends on how compact (dense) a substance is.
Power is the rate at which:
potential energy is converted into kinetic energy |
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friction is overcome |
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work is done |
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input force is transferred to output force |
Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newton-meter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. 1 hp equals 746 watts.
| 2.9 | |
| 2.4 | |
| 0.9 | |
| 2.7 |
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 = \( \frac{N_1}{N_2} \) = \( \frac{32}{12} \) = 2.7
Specific gravity is a comparison of the density of an object with the density of:
air |
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water |
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carbon |
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oil |
Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.
| 12 | |
| 27 | |
| 9 | |
| 11 |
The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In this case, the effort distance is the length of the ramp and the resistance distance is the height of the green box:
MA = \( \frac{d_e}{d_r} \) = \( \frac{63 ft.}{7 ft.} \) = 9