| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.74 |
| Score | 0% | 55% |
| 18 ft. | |
| 9 ft. | |
| 72 ft. | |
| 36 ft. |
To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:
Rada = Rbdb
where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.Solving for da, our missing value, and plugging in our variables yields:
da = \( \frac{R_bd_b}{R_a} \) = \( \frac{60 lbs. \times 3 ft.}{10 lbs.} \) = \( \frac{180 ft⋅lb}{10 lbs.} \) = 18 ft.
A wedge converts force applied to its blunt end into force __________ its inclined surface.
parallel to |
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opposite to |
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perpendicular to |
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along |
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.
The measure of how much of the power put into a machine is turned into movement or force is called:
mechanical advantage |
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power |
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force multiplication |
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efficiency |
The efficiency of a machine describes how much of the power put into the machine is turned into movement or force. A 100% efficient machine would turn all of the input power into output movement or force. However, no machine is 100% efficient due to friction, heat, wear and other imperfections that consume input power without delivering any output.
Depending on where you apply effort and resistance, the wheel and axle can multiply:
speed or power |
|
power or distance |
|
force or distance |
|
force or speed |
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 characteristic of a ceramic?
low density |
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low corrosive action |
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chemically stable |
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high melting point |
Ceramics are mixtures of metallic and nonmetallic elements that withstand exteme thermal, chemical, and pressure environments. They have a high melting point, low corrosive action, and are chemically stable. Examples include rock, sand, clay, glass, brick, and porcelain.