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Electronics Information

You would measure the amount of voltage between two points in a circuit with a(n):

voltmeter

Voltage (V) is the electrical potential difference between two points. A voltmeter is used to measure the voltage between two points in a circuit.

Arithmetic Reasoning

What is -5a⁶ - a⁶?

-6a⁶

To add or subtract terms with exponents, both the base and the exponent must be the same. In this case they are so subtract the coefficients and retain the base and exponent:

-5a⁶ - 1a⁶
(-5 - 1)a⁶
-6a⁶

Mechanical Comprehension

If the green box is 8 ft. from the fulcrum and a certain force applied 7 ft. from the fulcrum at the blue arrow balances the lever, what is the mechanical advantage?

0.88

Because this lever is in equilibrium, we know that the effort force at the blue arrow is equal to the resistance weight of the green box. For a lever that's in equilibrium, one method of calculating mechanical advantage (MA) is to divide the length of the effort arm (E_a) by the length of the resistance arm (R_a):

MA = \( \frac{E_a}{R_a} \) = \( \frac{7 ft.}{8 ft.} \) = 0.88

When a lever is in equilibrium, the torque from the effort and the resistance are equal. The equation for equilibrium is R_ad_a = R_bd_b where a and b are the two points at which effort/resistance is being applied to the lever.

In this problem, R_a and R_b are such that the lever is in equilibrium meaning that some multiple of the weight of the green box is being applied at the blue arrow. For a lever, this multiple is a function of the ratio of the distances of the box and the arrow from the fulcrum. That's why, for a lever in equilibrium, only the distances from the fulcrum are necessary to calculate mechanical advantage.

If the lever were not in equilibrium, you would first have to calculate the forces and distances necessary to put it in equilibrium and then divide E_a by R_a to get the mechanical advantage.

Electronics Information

An engineer who wants to document an electric circuit would create which of the following?

a schematic

A schematic is the proper name for a drawing of an electric or electronic circuit.

Shop Information

Which of the following tools are you more likely to use when woodworking?

chisel

A chisel has a long sharp edge and is used, often in conjunction with a hammer, for cutting. In woodworking, chisels are used to remove large sections of wood to create the initial shape of a design. In metalworking, chisels are used to remove waste metal when a smooth finish is not required.

Word Knowledge

Buffer most nearly means:

cushion

Protective barrier.

Mechanical Comprehension

A mass of air has a pressure of 6.0 psi and a volume of 30 ft.³. If the air is compressed to a new volume of 10 ft.³, what is the new pressure?

18 psi

According to Boyle's Law, pressure and volume are inversely proportional:

\( \frac{P_1}{P_2} \) = \( \frac{V_2}{V_1} \)

In this problem, V₂ = 10 ft.³, V₁ = 30 ft.³ and P₁ = 6.0 psi. Solving for P₂:

P₂ = \( \frac{P_1}{\frac{V_2}{V_1}} \) = \( \frac{6.0 psi}{\frac{10 ft.^3}{30 ft.^3}} \) = 18 psi

Electronics Information

Voltage and current are __________ proportional.

directly

Voltage (V) is the electrical potential difference between two points. Electrons will flow as current from areas of high potential (concentration of electrons) to areas of low potential. Voltage and current are directly proportional in that the higher the voltage applied to a conductor the higher the current that will result.

Word Knowledge

Pretentious most nearly means:

pompous

Making unjustified claims.

Mechanical Comprehension

Friction between two or more solid objects that are not moving relative to each other is called:

static friction

Static friction is friction between two or more solid objects that are not moving relative to each other. An example is the friction that prevents a box on a sloped surface from sliding farther down the surface.