| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.93 |
| Score | 0% | 59% |
Specific gravity is a comparison of the density of an object with the density of:
carbon |
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oil |
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air |
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water |
Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.
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.
Lisa lifts a 25 pound box from the floor onto a loading dock 4 ft. off the ground. Sam slides the same box along a ramp to move it up another 4 ft. onto a flatbed truck. Who has done more work?
Sam |
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Lisa |
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Neither have done any work |
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They have done an equal amount of work |
Work is force multiplied by distance. Because both Connie and Sam moved the same weight the same distance they have done an equal amount of work. Sam employed the mechnacial advantage of an inclined plane so he exerted less effort to do the work but the amount of work done was still the same.
Which of the following will increase the mechanical advantage of this inclined plane?
lower the force acting at the blue arrow |
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shorten the ramp |
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increase the force acting at the blue arrow |
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lengthen the ramp |
The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In order to increase mechanical advantage, this ratio must increase which means making the effort distance longer and this can be accomplished by lengthening the length of the ramp.
Gear ratio indicates which of the following about two connected gears?
power conversion |
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mechanical advantage |
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work done |
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efficiency |
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.