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Electronics Information

In electrical wiring, which of the following are proportional?

the diameter of the wire and the amount of the current

Current flow through a wire increases the temperature of the wire. If too small a wire is used, the wire will heat up causing a loss in conductivity and possibly a fire. The thicker in diameter a wire is, the more current it can carry without overheating.

General Science

Which of Earth's layers has weather?

troposphere

The Earth's atmosphere has several layers starting with the troposphere which is closest in proximity to the surface. Containing most of the Earth's breathable air (oxygen and nitrogen), it's a region with warmer temperatures closer to the surface and cooler temperatures farther away which results in the rising and falling air that generates weather.

General Science

__________ and __________ pair to strengthen bones.

vitamin D, calcium

Vitamin D helps calcium strengthen bones while also aiding muscle, nerve, and immune system function.

Mechanical Comprehension

Coplanar forces:

act in a common plane

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

Electronics Information

In household electrical wiring, which color of insulation indicates the 'hot' wire?

black

In the NM cable used for wiring homes, each cable has three wires inside a sheath with each wire covered in a different color of insulation to indicate its type. The wire with the black insulation is the 'hot' wire, white is the neutral wire, and the ground wire is either covered in green insulation or left bare.

Mechanical Comprehension

If you lift a 30 lbs. rock 24 ft. from the ground, how much work have you done?

720 ft⋅lb

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 30 \times 24 \)
\( W = 720 \)

General Science

When the clouds become too saturated with water, the water is released as precipitation in the form of:

snow

Rising into the atmosphere, the water condenses into clouds. When the clouds become too saturated with water, the water is released as snow or ice precipitation which may warm as it falls to reach Earth as rain.

Mechanical Comprehension

If the green box weighs 20 lbs. and is 1 ft. from the fulcrum, how far from the fulcrum would a 70 lbs. force need to be applied to balance the lever?

0.29 ft.

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 d_b, our missing value, and plugging in our variables yields:

d_b = \( \frac{R_ad_a}{R_b} \) = \( \frac{20 lbs. \times 1 ft.}{70 lbs.} \) = \( \frac{20 ft⋅lb}{70 lbs.} \) = 0.29 ft.

Electronics Information

The diameter of a number 12 wire is __________ the diameter of a number 6 wire?

less than

The larger the number the smaller the diameter of the wire. So, the diameter of a number 12 wire is less than the diameter of a number 6 wire.

Electronics Information

Direct current flows from the __________ terminal of the voltage source to the __________ terminal.

negative, positive

Direct current flows in only one direction in a circuit, from the negative terminal of the voltage source to the positive. A common source of direct current (DC) is a battery.