| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.45 |
| Score | 0% | 69% |
The mechanical advantage of a block and tackle is equal to which of the following?
the number of pulleys |
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the number of loads |
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the number of connecting ropes |
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the number of input forces |
Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement. So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.
Collinear forces:
act along the same line of action |
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act in a common plane |
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pass through a common point |
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are unrelated to each other |
Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.
| 3 | |
| 2.0 | |
| -3 | |
| 0.5 |
The mechanical advantage of a wheel and axle is the input radius divided by the output radius:
MA = \( \frac{r_i}{r_o} \)
In this case, the input radius (where the effort force is being applied) is 6 and the output radius (where the resistance is being applied) is 3 for a mechanical advantage of \( \frac{6}{3} \) = 2.0
The force required to initally get an object moving is __________ the force required to keep it moving.
the same as |
|
higher than |
|
lower than |
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opposite |
For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).
| 5 ft⋅lb | |
| 0 ft⋅lb | |
| 45 ft⋅lb | |
| 15 ft⋅lb |