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Unlike curved mirrors that operate on the principle of reflection, lenses utilize refraction. A convex lens is thicker in the middle than on the edges and converges light while a concave lens is thicker on the edges than in the middle and diffuses light. A common use for curved lenses is in eye glasses where a convex lens is used to correct farsightedness and a concave lens is used to correct nearsightedness.

The volume of a cylinder is πr²h:

v = πr²h
v = π(1² x 9)
v = 9π

The ripsaw delivers maximum efficiency at cutting with or along the grain (ripping).

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

7a + 6a = 13a

To simplify this fraction, first find the greatest common factor between them. The factors of 24 are [1, 2, 3, 4, 6, 8, 12, 24] and the factors of 56 are [1, 2, 4, 7, 8, 14, 28, 56]. They share 4 factors [1, 2, 4, 8] making 8 their greatest common factor (GCF).

Next, divide both numerator and denominator by the GCF:

\( \frac{24}{56} \) = \( \frac{\frac{24}{8}}{\frac{56}{8}} \) = \( \frac{3}{7} \)

The transmission provides the appropriate power to vehicle wheels to maintain a given speed. The engine and the transmission have to be disconnected to shift gears and a manual transmission requires the driver to manually manage this disconnection (using a clutch) and to manually shift gears. An automatic transmission is essentially an automatic gear shifter and handles this process without driver input.

Micrometers provide accuracy to the thousandths of an inch and come in outside and inside varieties. An outside micrometer is used to measure outside thickness, such as the diameter of a bolt, while an inside micrometer is used to measure the inside dimension of an object, such as the diameter of the hole of a nut or the width of a channel.

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.

Part of the brainstem, the medulla is the connection between the brain and the spinal cord. It controls involuntary actions like breathing, swallowing, and heartbeat.

The absolute value is the positive magnitude of a particular number or variable and is indicated by two vertical lines: \(\left|-5\right| = 5\). In the case of a variable absolute value (\(\left|a\right| = 5\)) the value of a can be either positive or negative (a = -5 or a = 5).