| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.77 |
| Score | 0% | 55% |
Which of the following represents how much two materials resist sliding across each other?
coefficient of friction |
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normal friction |
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static friction |
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kinetic 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 principle of conservation of mechanical energy states that, as long as no other forces are applied, what will remain constant as an object falls?
total mechanical energy |
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potential energy |
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acceleration |
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kinetic energy |
As an object falls, its potential energy is converted into kinetic energy. The principle of conservation of mechanical energy states that, as long as no other forces are applied, total mechanical energy (PE + KE) of the object will remain constant at all points in its descent.
A wedge converts force applied to its blunt end into force __________ its inclined surface.
parallel to |
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opposite to |
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perpendicular to |
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along |
The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.
Depending on where you apply effort and resistance, the wheel and axle can multiply:
force or distance |
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power or distance |
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force or speed |
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speed or power |
If you apply the resistance to the axle and the effort to the wheel, the wheel and axle will multiply force and if you apply the resistance to the wheel and the effort to the axle, it will multiply speed.
The mechanical advantage of connected gears is proportional to which characteristic of the gears?
circumference |
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diameter |
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number of teeth |
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speed |
The mechanical advantage (amount of change in speed or torque) of connected gears is proportional to the number of teeth each gear has. Called gear ratio, it's the ratio of the number of teeth on the larger gear to the number of teeth on the smaller gear. For example, a gear with 12 teeth connected to a gear with 9 teeth would have a gear ratio of 4:3.