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Electronics Information

Current is the rate of flow of electrons per unit time and is measured in:

amperes

Current is the rate of flow of electrons per unit time and is measured in amperes (A). A coulomb (C) is the quantity of electricity conveyed in one second by a current of one ampere.

Arithmetic Reasoning

What is \( \frac{3}{3} \) - \( \frac{5}{5} \)?

To subtract these fractions, first find the lowest common multiple of their denominators. The first few multiples of 3 are [3, 6, 9, 12, 15, 18, 21, 24, 27, 30] and the first few multiples of 5 are [5, 10, 15, 20, 25, 30, 35, 40, 45, 50]. The first few multiples they share are [15, 30, 45, 60, 75] making 15 the smallest multiple 3 and 5 share.

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

\( \frac{3 x 5}{3 x 5} \) - \( \frac{5 x 3}{5 x 3} \)

\( \frac{15}{15} \) - \( \frac{15}{15} \)

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

\( \frac{15 - 15}{15} \) = \( \frac{0}{15} \) =

Word Knowledge

Mandate most nearly means:

command

An official order or commission to do something.

General Science

Sound travels fastest through which of the following media?

metal

The speed of a sound wave will vary with the medium. Sound travels fastest through media that has particles that are very close together, like metal. Thus, it travels faster through water than through air and doesn't travel at all through a vacuum (there are no particles in empty space to vibrate).

Mechanical Comprehension

If the radius of the axle is 5 and the radius of the wheel is 6, what is the mechanical advantage of this wheel and axle configuration?

1.2

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 5 for a mechanical advantage of \( \frac{6}{5} \) = 1.2

Word Knowledge

Duplicity most nearly means:

deceit

Deceptive thought, speech, or action.

Word Knowledge

Futile most nearly means:

hopeless

Without purpose, completely ineffective.

Electronics Information

What's the overall power consumption of a piece of equipment that is rated for 7 amps at 60 volts?

420 W

Power is measured in watts (W) and 1 watt equals 1 ampere multiplied by 1 volt: P = \( V \times I \). For this problem, the equipment is rated for 7 amps (I) at 60 volts (V) so the equation becomes P = \( 60 \times 7 \) = 420 W

Automotive Information

Just before the piston reaches top dead center, the spark plug fires and ignites the compressed air-fuel mixture. This describes which engine stroke?

power

During the power stroke, just before the piston reaches top dead center, the spark plug fires and ignites the compressed air-fuel mixture. The resulting expansion due to combustion pushes the piston back down the cylinder toward bottom dead center.

Automotive Information

Ignition timing is measured in number of degrees:

before top dead center

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.