| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.15 |
| Score | 0% | 63% |
Which of the following is not a characteristic of a ceramic?
chemically stable |
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low density |
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high melting point |
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low corrosive action |
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.
A screw is most like which of the following other simple machines?
inclined plane |
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wheel and axle |
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first-class lever |
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block and tackle |
A screw is an inclined plane wrapped in ridges (threads) around a cylinder. The distance between these ridges defines the pitch of the screw and this distance is how far the screw advances when it is turned once. The mechanical advantage of a screw is its circumference divided by the pitch.
Which of the following is the formula for gravitational potential energy?
\(PE = mgh\) |
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\(PE = { 1 \over 2} mv^2\) |
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\(PE = mg^2h\) |
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\(PE = { 1 \over 2} mg^2\) |
Gravitational potential energy is energy by virtue of gravity. The higher an object is raised above a surface the greater the distance it must fall to reach that surface and the more velocity it will build as it falls. For gravitational potential energy, PE = mgh where m is mass (kilograms), h is height (meters), and g is acceleration due to gravity which is a constant (9.8 m/s2).
What is work?
Force per unit distance |
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Force per unit time |
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The movement of an object by a force |
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The potential for exertion |
Work is accomplished when force is applied to an object: W = Fd where F is force in newtons (N) and d is distance in meters (m). Thus, the more force that must be applied to move an object, the more work is done and the farther an object is moved by exerting force, the more work is done. By definition, work is the displacement of an object resulting from applied force.
Drag is a type of:
potential energy |
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work |
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kinetic energy |
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friction |
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.