| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.37 |
| Score | 0% | 67% |
The mass of an object correlates to the size of the object but ultimately depends on:
the object's potential energy |
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gravity |
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the object's weight |
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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.
Sam can do 50 ft. lb. of work in 2 minutes and 5 seconds. What would Sam have to do to increase his power output?
do 25 ft. lb. of work in 2 minutes 5 seconds |
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do the work in 2 minutes |
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do the work in 3 minutes |
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do 100 ft. lb. of work in 4 minutes 12 seconds |
Power is the rate of doing work or \(\frac{W}{t}\). To increase power, increase the work being done in the same amount of time or do the same amount of work in less time.
Power is the rate at which:
friction is overcome |
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work is done |
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input force is transferred to output force |
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potential energy is converted into kinetic energy |
Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newton-meter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. 1 hp equals 746 watts.
An inclined plane increases ___________ to reduce ____________.
force, distance |
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distance, power |
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force, power |
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distance, force |
An inclined plane is a simple machine that reduces the force needed to raise an object to a certain height. Work equals force x distance and, by increasing the distance that the object travels, an inclined plane reduces the force necessary to raise it to a particular height. In this case, the mechanical advantage is to make the task easier. An example of an inclined plane is a ramp.
On Earth, acceleration due to gravity (g) is approximately __________.
6.67 x 10-11 m/s2 |
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9.8 m/s2 |
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1 m/s2 |
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1 m/s |
Newton's Law of Univeral Gravitation defines the general formula for the attraction of gravity between two objects: \(\vec{F_{g}} = { Gm_{1}m_{2} \over r^2}\) . In the specific case of an object falling toward Earth, the acceleration due to gravity (g) is approximately 9.8 m/s2.