| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.74 |
| Score | 0% | 55% |
| 16.5 | |
| 3.7 | |
| 11 | |
| 12.5 |
The mechanical advantage of a gear train is its gear ratio. The gear ratio (Vr) 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 three gears so the equation becomes:
Vr = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) = \( \frac{22}{12} \) \( \frac{12}{2} \) = \( \frac{22}{2} \) = 11
Which of the following will increase the mechanical advantage of this inclined plane?
increase the force acting at the blue arrow |
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shorten the ramp |
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lengthen the ramp |
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lower the force acting at the blue arrow |
The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In order to increase mechanical advantage, this ratio must increase which means making the effort distance longer and this can be accomplished by lengthening the length of the ramp.
Which of the following is not a characteristic of a ceramic?
chemically stable |
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low density |
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low corrosive action |
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high melting point |
Ceramics are mixtures of metallic and nonmetallic elements that withstand exteme thermal, chemical, and pressure environments. They have a high melting point, low corrosive action, and are chemically stable. Examples include rock, sand, clay, glass, brick, and porcelain.
Specific gravity is a comparison of the density of an object with the density of:
carbon |
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oil |
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air |
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water |
Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.
Which of the following statements about this pulley configuration is false?
Only multiplies the effort force |
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Changes the direction of and multiplies the effort force |
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This is a block and tackle pulley configuration |
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Mechanical advantage is the number of ropes that support the resistance |
A block and tackle is a combination of one or more fixed pulleys and one or more movable pulleys where the fixed pulleys change the direction of the effort force and the movable pulleys multiply it. The mechanical advantage is equal to the number of times the effort force changes direction and can be increased by adding more pulley wheels to the system. An easy way to find the mechanical advantage of a block and tackle pulley system is to count the number of ropes that support the resistance.