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Mechanical Comprehension

If 15 lbs. of force is applied 8 ft. from the fulcrum at the blue arrow and the green box is 7 ft. from the fulcrum, how much would the green box have to weigh to balance the lever?

17.14 lbs.

To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

R_ad_a = R_bd_b

where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.

Solving for R_a, our missing value, and plugging in our variables yields:

R_a = \( \frac{R_bd_b}{d_a} \) = \( \frac{15 lbs. \times 8 ft.}{7 ft.} \) = \( \frac{120 ft⋅lb}{7 ft.} \) = 17.14 lbs.

Word Knowledge

The executive was fired for his flagrant abuse of the company expense account.

glaring

Noticeably offensive.

Word Knowledge

Censure most nearly means:

blame

To find fault with.

Word Knowledge

Punctual most nearly means:

prompt

On time.

General Science

In the Periodic Table of the Elements, atomic number is equal to which of the following?

number of protons in the nucleus

The Periodic Table of the Elements categorizes elements primarily by the number of protons in their nucleus (atomic number) and secondarily by the characteristics they exhibit.

Word Knowledge

Rehash most nearly means:

review

To discuss again.

Arithmetic Reasoning

On average, the center for a basketball team hits 50% of his shots while a guard on the same team hits 60% of his shots. If the guard takes 25 shots during a game, how many shots will the center have to take to score as many points as the guard assuming each shot is worth the same number of points?

If the guard hits 60% of his shots and takes 25 shots he'll make:

guard shots made = shots taken x \( \frac{\text{% made}}{100} \) = 25 x \( \frac{60}{100} \) = \( \frac{60 x 25}{100} \) = \( \frac{1500}{100} \) = 15 shots

The center makes 50% of his shots so he'll have to take:

shots made = shots taken x \( \frac{\text{% made}}{100} \)
shots taken = \( \frac{\text{shots taken}}{\frac{\text{% made}}{100}} \)

to make as many shots as the guard. Plugging in values for the center gives us:

center shots taken = \( \frac{15}{\frac{50}{100}} \) = 15 x \( \frac{100}{50} \) = \( \frac{15 x 100}{50} \) = \( \frac{1500}{50} \) = 30 shots

to make the same number of shots as the guard and thus score the same number of points.

Automotive Information

The spark plugs fire a few extra degrees before top dead center when the engine is running faster. In this case the engine's timing is:

advanced

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.

Electronics Information

What kind of diode allows current to flow in the opposite direction once a certain voltage threshold is reached?

zener diode

A diode allows current to pass easily in one direction and blocks current in the other direction. A zener diode is a diode which allows current to flow in one direction as normal and will also allow current flow in the reverse direction when the voltage is above a certain value. This value is called the breakdown voltage.

Shop Information

Screwdrivers are most broadly classified by their:

tip

Screwdrivers come in many different handle, shaft, and tip configurations for use in a wide variety of applications. Screwdrivers are classified by their tip which is shaped to fit a corresponding screw head. Common tips are slotted (flat) and Phillips (x-shaped).