| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.37 |
| Score | 0% | 67% |
An object's resistance to changes in direction is known as:
mass |
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inertia |
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kinetic energy |
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weight |
The more mass a substance has the more force is required to move it or to change its direction. This resistance to changes in direction is known as inertia.
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?
potential energy |
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total mechanical 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 is most similar to what other type of simple machine?
inclined plane |
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third-class lever |
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first-class lever |
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second-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.
| 875 lbs. | |
| 1750 lbs. | |
| 1925 lbs. | |
| 3500 lbs. |
The mechanical advantage (MA) of a block and tackle pulley is equal to the number of times the effort force changes direction. An easy way to count how many times the effort force changes direction is to count the number of ropes that support the resistance which, in this problem, is 10. With a MA of 10, a 175 lbs. effort force could lift 175 lbs. x 10 = 1750 lbs. resistance.
Gear ratio indicates which of the following about two connected gears?
work done |
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power conversion |
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mechanical advantage |
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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.