Explanation

The SI is made up of 7 base units

that define the 22 derived units with special names and symbols, which are illustrated in NIST SP 1247, SI Base Units Relationship Poster. 

Explanation

An optical fiber is a flexible,

transparent fiber made by drawing glass  or plastic

To a diameter slightly thicker than that of a human hair.

Explanation

Explanation

• The SI unit of energy is the Joule (J).
• It is the unit of energy, work, and heat.

Explanation

• Sound travels fastest in diamond, with a speed of approximately 12,000 meters per second (m/s).
• This is because diamond has a very high stiffness and density, which allows sound waves to propagate quickly through the material.

The speeds of sound in different materials:

• Air: 343 m/s
• Water: 1433 m/s
• Wood: 3300-3600 m/s
• Brick: 4176 m/s
• Steel: 6100 m/s
• Diamond: 12000 m/s

Explanation

Decibels measure sound intensity (amplitude)

Sound is energy that travels in waves.

It can be measured in two ways: frequency and amplitude.

Explanation

A galaxy is a gravitational system of stars, star remnants, interstellar gas, dust, and dark matter.

Earth: diameter of approximately 12,742 kilometers (7,918 miles)

The Sun: diameter of approximately 1,392,684 kilometers (865,374 miles)

Solar System: diameter of approximately 9.2 billion kilometers (5.7 billion miles)

Galaxy (Milky Way): diameter of approximately 100,000 to 200,000 light-years (9.461 × 10^17 to 1.884 × 10^18 kilometers)

Explanation

Explanation

Explanation

The mass per unit volume of a substance is called density (density = mass/volume).

• The formula of Density is: D=m/v
• ****
• Here D is density,
• M is mass &
• V is Volume.
• Density is commonly expressed in units of grams per cubic centimeter.
• The standard units are kg/m³