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Mechanical Comprehension

A shovel is an example of which class of lever?

third

A third-class lever is used to increase distance traveled by an object in the same direction as the force applied. The fulcrum is at one end of the lever, the object at the other, and the force is applied between them. This lever does not impart a mechanical advantage as the effort force must be greater than the load but does impart extra speed to the load. Examples of third-class levers are shovels and tweezers.

Automotive Information

Which of the following is not a primary function of a vehicle's lubrication system?

increases fuel economy

The lubrication system lubricates engine components by putting an oil film between them to reduce friction and smooth engine operation, cools by absorbing heat from engine parts, seals the pistons and cylinders to contain combustion, cleans contaminants, and quiets engine noise.

Mechanical Comprehension

If the force applied at the blue arrow over 5 ft. moves the green box 2.5 ft., what is the mechanical advantage of this lever?

Mechanical advantage (MA) can be calculated knowing only the distance the effort (blue arrow) moves and the distance the resistance (green box) moves. The equation is:

MA = \( \frac{E_d}{R_d} \)

where E_d is the effort distance and R_d is the resistance distance. For this problem, the equation becomes:

MA = \( \frac{5 ft.}{2.5 ft.} \) = 2

You might be wondering how having an effort distance of 2 times the resistance distance is an advantage. Remember the principle of moments. For a lever in equilibrium the effort torque equals the resistance torque. Because torque is force x distance, if the effort distance is 2 times the resistance distance, the effort force must be \( \frac{1}{2} \) the resistance force. You're trading moving 2 times the distance for only having to use \( \frac{1}{2} \) the force.

Electronics Information

Which of the following allows encapsulating complex circuit designs for easier integration into electronic devices and machines?

integrated circuits

Circuits containing transistors are packaged into integrated circuit chips that allow encapsulating complex circuit designs (CPU, memory, I/O) for easier integration into electronic devices and machines.

Math Knowledge

The endpoints of this line segment are at (-2, 2) and (2, -6). What is the slope-intercept equation for this line?

y = -2x - 2

The slope-intercept equation for a line is y = mx + b where m is the slope and b is the y-intercept of the line. From the graph, you can see that the y-intercept (the y-value from the point where the line crosses the y-axis) is -2. The slope of this line is the change in y divided by the change in x. The endpoints of this line segment are at (-2, 2) and (2, -6) so the slope becomes:

m = \( \frac{\Delta y}{\Delta x} \) = \( \frac{(-6.0) - (2.0)}{(2) - (-2)} \) = \( \frac{-8}{4} \)
m = -2

Plugging these values into the slope-intercept equation:

y = -2x - 2

Math Knowledge

Which of the following expressions contains exactly two terms?

binomial

A monomial contains one term, a binomial contains two terms, and a polynomial contains more than two terms.

Word Knowledge

Derivative most nearly means:

banal

Lacking originality.

Word Knowledge

Refurbish most nearly means:

renovate

To brighten or freshen.

Automotive Information

Another name for the powertrain control module is the __________ control unit.

engine

The main computer or powertrain control module (PCM) uses pre-programmed software to analyze the input received from sensors and produce output signals to adjust vehicle performance and operation. (Engine control unit (ECU) is another name for the PCM.)

Automotive Information

Coolant is circulated through the engine by the:

water pump

The water pump is driven by a belt connected to the crankshaft and ensures that coolant moves through the engine and radiator.