| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.16 |
| Score | 0% | 63% |
Which of the following surfaces would have the lowest coefficient of friction?
leather |
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ice |
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concrete |
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tile |
Coefficient of friction (μ) represents how much two materials resist sliding across each other. Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.
A fixed pulley is useful for which of the following?
changing the direction of the input force |
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multiplying the input force |
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changing the direction of the output force |
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multiplying the input distance |
A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.
Which of the following will increase the mechanical advantage of a second-class lever?
move the object being lifted farther away from the fulcrum |
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move the object being lifted closer to the fulcrum |
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move the fulcrum between the force and the object being lifted |
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decrease the length of the lever |
A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.
A fixed pulley has a mechanical advantage of:
-1 |
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1 |
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0 |
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2 |
A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.
Which class of lever is used to increase force on an object in the same direction as the force is applied?
first |
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all of these |
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third |
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second |
A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.