| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.90 |
| Score | 0% | 58% |
The science that deals with motion and the forces that produce motion is called which of the following?
mechanics |
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physics |
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engineering |
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aeronautics |
Mechanics deals with motion and the forces that produce motion.
Which of the following is not a characteristic of a ceramic?
low corrosive action |
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chemically stable |
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low density |
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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.
Which of these will have the most impact on the kinetic energy of an object?
its speed |
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its weight |
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its direction |
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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.
The mechanical advantage of a block and tackle is equal to which of the following?
the number of pulleys |
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the number of loads |
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the number of input forces |
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the number of connecting ropes |
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.
| 22.5 | |
| 11 | |
| 15 | |
| 45 |
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 = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) = \( \frac{30}{14} \) \( \frac{14}{2} \) = \( \frac{30}{2} \) = 15