| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.17 |
| Score | 0% | 63% |
Which of the following represents how much two materials resist sliding across each other?
kinetic friction |
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normal friction |
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static friction |
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coefficient of friction |
Coefficient of friction (μ) represents how much two materials resist sliding across each other. Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.
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 input forces |
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the number of connecting ropes |
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the number of loads |
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.
The mass of an object correlates to the size of the object but ultimately depends on:
the object's weight |
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the object's potential energy |
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gravity |
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the object's density |
Mass is a measure of the amount of matter in an object. In general, larger objects have larger mass than smaller objects but mass ultimately depends on how compact (dense) a substance is.
| 9 psi | |
| 13.5 psi | |
| 27 psi | |
| 9.9 psi |
According to Boyle's Law, pressure and volume are inversely proportional:
\( \frac{P_1}{P_2} \) = \( \frac{V_2}{V_1} \)
In this problem, V2 = 20 ft.3, V1 = 30 ft.3 and P1 = 6.0 psi. Solving for P2:
P2 = \( \frac{P_1}{\frac{V_2}{V_1}} \) = \( \frac{6.0 psi}{\frac{20 ft.^3}{30 ft.^3}} \) = 9 psi
The standard unit of energy is the:
Watt |
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Joule |
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Volt |
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Horsepower |
The Joule (J) is the standard unit of energy and has the unit \({kg \times m^2} \over s^2\).