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Automotive Information

Gases from combustion are pushed out through the exhaust valve as the piston travels up the cylinder to top dead center. This describes which engine stroke?

exhaust

During the exhaust stroke, just before the piston reaches bottom dead center the exhaust valve opens. The resulting gases from combustion are then pushed out through the exhaust valve as the piston travels up the cylinder to top dead center, completing stroke four of the four-stroke piston cycle.

General Science

In the classification of life, bacteria, archaea and eukaryota are which of the following?

domains

The broadest classification of life splits all organisms into three groups called domains. The three domains of life are bacteria, archaea and eukaryota.

Automotive Information

What function does a two-stroke cycle engine perform on the second stroke?

combustion and exhaust

The two strokes of a two-stroke cycle engine are fuel intake and compression then combustion and exhaust.

Math Knowledge

Solve for z:
z² - 5z - 6 = 0

-1 or 6

The first step to solve a quadratic equation that's set to zero is to factor the quadratic equation:

z² - 5z - 6 = 0
(z + 1)(z - 6) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (z + 1) or (z - 6) must equal zero:

If (z + 1) = 0, z must equal -1
If (z - 6) = 0, z must equal 6

So the solution is that z = -1 or 6

Mechanical Comprehension

Tension is a force that does which of the following?

stretches an object

Tension is a force that stretches or elongates something. When a cable or rope is used to pull an object, for example, it stretches internally as it accepts the weight that it's moving. Although tension is often treated as applying equally to all parts of a material, it's greater at the places where the material is under the most stress.

General Science

The __________ nervous system controls voluntary actions.

somatic

Part of the peripheral nervous system, the somatic nervous system is made up of nerve fibers that send sensory information to the central nervous system and control voluntary actions.

Arithmetic Reasoning

A machine in a factory has an error rate of 6 parts per 100. The machine normally runs 24 hours a day and produces 5 parts per hour. Yesterday the machine was shut down for 6 hours for maintenance.

How many error-free parts did the machine produce yesterday?

84.6

The hourly error rate for this machine is the error rate in parts per 100 multiplied by the number of parts produced per hour:

\( \frac{6}{100} \) x 5 = \( \frac{6 \times 5}{100} \) = \( \frac{30}{100} \) = 0.3 errors per hour

So, in an average hour, the machine will produce 5 - 0.3 = 4.7 error free parts.

The machine ran for 24 - 6 = 18 hours yesterday so you would expect that 18 x 4.7 = 84.6 error free parts were produced yesterday.

Word Knowledge

Iridescent most nearly means:

shimmering

Having a lustrous or attractivve quality.

Mechanical Comprehension

If A = 9 ft. and the green box weighs 30 lbs. what is the torque acting on the A side of this lever?

270 ft⋅lb

For a lever, torque is weight x distance from the fulcrum which, in this case, is: 30 ft. x 9 lbs. = 270 ft⋅lb

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