| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.07 |
| Score | 0% | 61% |
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.
Friction between two or more solid objects that are not moving relative to each other is called:
dynamic friction |
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kinetic friction |
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static friction |
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gravitational friction |
Static friction is friction between two or more solid objects that are not moving relative to each other. An example is the friction that prevents a box on a sloped surface from sliding farther down the surface.
| 9 ft. | |
| 135 ft. | |
| 4.5 ft. | |
| 36 ft. |
To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:
Rada = Rbdb
where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.Solving for db, our missing value, and plugging in our variables yields:
db = \( \frac{R_ad_a}{R_b} \) = \( \frac{45 lbs. \times 3 ft.}{15 lbs.} \) = \( \frac{135 ft⋅lb}{15 lbs.} \) = 9 ft.
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.
Which of the following is not a type of simple machine?
pulley |
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gear |
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screw |
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lever |
The six types of simple machines are the lever, wheel and axle, pulley, inclined plane, wedge, and screw.