| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.50 |
| Score | 0% | 50% |
Which of the following is not a characteristic of a ceramic?
high melting point |
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low corrosive action |
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chemically stable |
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low density |
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.
| 0.51 ft. | |
| 1.54 ft. | |
| 4 ft. | |
| 100 ft. |
To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:
Rada = Rbdb
where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.Solving for db, our missing value, and plugging in our variables yields:
db = \( \frac{R_ad_a}{R_b} \) = \( \frac{20 lbs. \times 5 ft.}{65 lbs.} \) = \( \frac{100 ft⋅lb}{65 lbs.} \) = 1.54 ft.
What's the last gear in a gear train called?
driven gear |
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driver gear |
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idler gear |
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output gear |
A gear train is two or more gears linked together. Gear trains are designed to increase or reduce the speed or torque outpout of a rotating system or change the direction of its output. The first gear in the chain is called the driver and the last gear in the chain the driven gear with the gears between them called idler gears.
| 1 | |
| 4 | |
| 3 | |
| 1 |
The mechanical advantage of a wheel and axle lies in the difference in radius between the inner (axle) wheel and the outer wheel. But, this mechanical advantage is only realized when the input effort and load are applied to different wheels. Applying both input effort and load to the same wheel results in a mechanical advantage of 1.
What type of load creates different stresses at different locations on a structure?
impact load |
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non-uniformly distributed load |
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static uniformly distributed load |
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dynamic load |
A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.