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Mechanical Comprehension

If the radius of the axle is 5 and the radius of the wheel is 8, what is the mechanical advantage of this wheel and axle configuration?

0.63

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 5 and the output radius (where the resistance is being applied) is 8 for a mechanical advantage of \( \frac{5}{8} \) = 0.63

Word Knowledge

Dubious most nearly means:

suspect

Questionable.

Mechanical Comprehension

For a hydraulic system, pressure applied to the input of the system will increase the pressure in which parts of the system?

all of these are correct

Pascal's law states that a pressure change occurring anywhere in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere. For a hydraulic system, this means that a pressure applied to the input of the system will increase the pressure everywhere in the system.

Word Knowledge

Rehash most nearly means:

review

To discuss again.

Automotive Information

Ignition timing defines the point in time at the end of the compression stroke that which of the following happens?

spark plugs fire

Ignition timing defines the point in time at the end of the compression stroke that the spark plug fires. Measured in number of degrees before top dead center (BTDC), the exact point that the spark plugs initiate combustion varies depending on the speed of the engine. The timing is advanced (the spark plugs fire a few more degrees BTDC) when the engine is running faster and retarded when it's running slower.

General Science

Which of the following is not part of the carbon cycle?

precipitation

The carbon cycle represents the ciruit of carbon through Earth's ecosystem. Carbon dioxide (CO₂) in the atmosphere is absorbed by plants through photosynthesis. Plants then die and release carbon back into the atmosphere during decomposition or are eaten by animals who breathe (respiration) the carbon into the atmosphere they exhale and produce waste which also releases carbon as it decays.

Mechanical Comprehension

A block and tackle with four pulleys would have a mechanical advantage of:

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.

Word Knowledge

The best–selling writer was disappointed; his new novel was only a moderate success.

medium

Tending toward the average.

Word Knowledge

Periodic most nearly means:

repeated

Occurring at regular intervals.

Arithmetic Reasoning

What is \( \frac{4}{6} \) + \( \frac{4}{14} \)?

\(\frac{20}{21}\)

To add these fractions, first find the lowest common multiple of their denominators. The first few multiples of 6 are [6, 12, 18, 24, 30, 36, 42, 48, 54, 60] and the first few multiples of 14 are [14, 28, 42, 56, 70, 84, 98]. The first few multiples they share are [42, 84] making 42 the smallest multiple 6 and 14 share.

Next, convert the fractions so each denominator equals the lowest common multiple:

\( \frac{4 x 7}{6 x 7} \) + \( \frac{4 x 3}{14 x 3} \)

\( \frac{28}{42} \) + \( \frac{12}{42} \)

Now, because the fractions share a common denominator, you can add them:

\( \frac{28 + 12}{42} \) = \( \frac{40}{42} \) = \(\frac{20}{21}\)