| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.12 |
| Score | 0% | 62% |
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 the work in 3 minutes |
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do 25 ft. lb. of work in 2 minutes 5 seconds |
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do 100 ft. lb. of work in 4 minutes 12 seconds |
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do the work in 2 minutes |
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.
A wedge is most similar to what other type of simple machine?
inclined plane |
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second-class lever |
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first-class lever |
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third-class lever |
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.
One Horsepower (hp) is equal to how many watts?
746 |
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9.8 |
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1 |
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1492 |
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.
The principle of moments defines equilibrium in terms of:
speed |
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torque |
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energy |
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power |
According to the principle of moments, you can maintain equilibrium if the moments (forces) tending to clockwise rotation are equal to the moments tending to counterclockwise rotation. Another name for these moments of force is torque.
A truck is using a rope to pull a car. Tension in the rope is greatest in which of the following places?
in the middle |
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tension is equal in all parts of the rope |
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near the car |
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near the truck |
Tension is a force that stretches or elongates something. When a cable or rope is used to pull an object, for example, it stretches internally as it accepts the weight that it's moving. Although tension is often treated as applying equally to all parts of a material, it's greater at the places where the material is under the most stress.