| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.16 |
| Score | 0% | 63% |
Which of the following is not a type of bridge?
block |
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arch |
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cable |
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truss |
The six basic bridge forms are beam, truss, arch, cantilever, cable, and suspension.
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 25 ft. lb. of work in 2 minutes 5 seconds |
|
do the work in 3 minutes |
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do the work in 2 minutes |
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do 100 ft. lb. of work in 4 minutes 12 seconds |
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.
The mechanical advantage of a block and tackle is equal to which of the following?
the number of loads |
|
the number of connecting ropes |
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the number of pulleys |
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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.
Specific gravity is a comparison of the density of an object with the density of:
carbon |
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oil |
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water |
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air |
Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.
| 3 | |
| 1.43 | |
| 0.7 | |
| 7 |
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 10 and the output radius (where the resistance is being applied) is 7 for a mechanical advantage of \( \frac{10}{7} \) = 1.43