| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.39 |
| Score | 0% | 68% |
Which of the following is not a characteristic of a ceramic?
low corrosive action |
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high melting point |
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low density |
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chemically stable |
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.
Potential energy is energy that has the potential to be converted into what?
heat |
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power |
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kinetic energy |
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work |
Potential energy is the energy of an object by virtue of its position relative to other objects. It is energy that has the potential to be converted into kinetic energy.
| 78 lbs. | |
| 26 lbs. | |
| 0 lbs. | |
| 156 lbs. |
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 Ra, our missing value, and plugging in our variables yields:
Ra = \( \frac{R_bd_b}{d_a} \) = \( \frac{65 lbs. \times 6 ft.}{5 ft.} \) = \( \frac{390 ft⋅lb}{5 ft.} \) = 78 lbs.
| 5.32 lbs. | |
| 30.08 lbs. | |
| 4.33 lbs. | |
| 3 lbs. |
The mechanical advantage of a wheel and axle is the input radius divided by the output radius:
MA = \( \frac{r_i}{r_o} \)
In this case, the input radius (where the effort force is being applied) is 4 and the output radius (where the resistance is being applied) is 3 for a mechanical advantage of \( \frac{4}{3} \) = 1.33
MA = \( \frac{load}{effort} \) so effort = \( \frac{load}{MA} \) = \( \frac{40 lbs.}{1.33} \) = 30.08 lbs.
Drag is a type of:
kinetic energy |
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friction |
|
work |
|
potential energy |
Drag is friction that opposes movement through a fluid like liquid or air. The amount of drag depends on the shape and speed of the object with slower objects experiencing less drag than faster objects and more aerodynamic objects experiencing less drag than those with a large leading surface area.