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Mechanical Comprehension

The force amplification achieved by using a tool, mechanical device or machine system is called:

mechanical advantage

Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Such a device utilizes input force and trades off forces against movement to amplify and/or change its direction.

Automotive Information

Both intake and exhaust valves are closed as the piston begins moving back up from the bottom of the cylinder, compressing the air-fuel mixture in the combustion chamber which also makes it hotter. This describes which engine stroke?

compression

During the compression stroke, both intake and exhaust valves are closed as the piston begins moving back up from the bottom of the cylinder (bottom dead center or BDC). This compresses the air-fuel mixture in the combustion chamber which also makes it hotter.

General Science

Which is the proper order of Earth's atmospheric layers from the surface up to space?

troposphere, stratosphere, mesosphere, thermosphere

The troposphere is the closest layer to Earth, followed by the stratosphere, mesosphere, and finally the thermosphere which borders space.

Word Knowledge

The sweet cookie was a perfect foil to the sour lemon sorbet.

complement

One that enhances or underscores by contrast.

Shop Information

Which of the following would be used to make a drilling guide mark in a sheet of metal?

center punch

A punch is narrow and is used to drive objects like nails (pin punch) or for making guide marks for drilling (center punch) or patterns in wood or metal.

General Science

Poor balance could indicate an issue with which part of the nervous system?

cerebellum

The cerebellum is a large cluster of nerves at the base of the brain that's responsible for balance, movement, and muscle coordination.

General Science

Saturated fats can __________ LDL ("bad") cholesterol while unsaturated fats can __________ it.

raise, decrease

Saturated fats can raise LDL ("bad") cholesterol while unsaturated fats can decrease it.

Math Knowledge

$4$ \sqrt{2} $$

If the area of this square is 16, what is the length of one of the diagonals?

4$ \sqrt{2} $

To find the diagonal we need to know the length of one of the square's sides. We know the area and the area of a square is the length of one side squared:

a = s²

so the length of one side of the square is:

s = $ \sqrt{a} $ = $ \sqrt{16} $ = 4

The Pythagorean theorem defines the square of the hypotenuse (diagonal) of a triangle with a right angle as the sum of the squares of the other two sides:

c² = a² + b²
c² = 4² + 4²
c² = 32
c = $ \sqrt{32} $ = $ \sqrt{16 x 2} $ = $ \sqrt{16} $ $ \sqrt{2} $
c = 4$ \sqrt{2} $

Shop Information

The __________ is an initial shallow saw cut made as a guide to prevent the saw from slipping sideways on subsequent more powerful cuts.

kerf

When you start sawing by creating a kerf it will help prevent the saw from slipping sideways when you begin the power strokes that do most of the cutting.

Mechanical Comprehension

If A = 10 ft., B = 1 ft., C = 9 ft., the green box weighs 50 lbs. and the blue box weighs 60 lbs., what does the orange box have to weigh for this lever to balance?

48.89 lbs.

In order for this lever to balance, the torque acting on each side of the fulrum must be equal. So, the torque produced by A must equal the torque produced by B and C. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

f_Ad_A = f_Bd_B + f_Cd_C

For this problem, this equation becomes:

50 lbs. x 10 ft. = 60 lbs. x 1 ft. + f_C x 9 ft.

500 ft. lbs. = 60 ft. lbs. + f_C x 9 ft.

f_C = $ \frac{500 ft. lbs. - 60 ft. lbs.}{9 ft.} $ = $ \frac{440 ft. lbs.}{9 ft.} $ = 48.89 lbs.