A Galaxy Is Observed Receding from Earth with a Speed

question 22

Multiple Choice

A galaxy is observed receding from Earth with a speed of 2800 km/s. If the Hubble constant is 22 km/s per million light-years, estimate how many years ago the light that we presently see from the galaxy actually left the galaxy. (c = 3.00 × 10⁸ m/s, 1 ly = 9.461 × 10¹⁵ m, 1 y = 3.156 × 10⁷ s)

• A) 1.3 × 10⁸ y
• B) 4.2 × 10⁸ y
• C) 4.2 × 10⁷ y
• D) 1.4 × 10⁷ y
• E) 4.2 × 10⁶ y

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Definitions:

Mucus

A sticky, thick fluid secreted by mucous membranes and glands, providing lubrication and protection in various parts of the body.

Gas Exchange

The biological process through which organisms exchange oxygen and carbon dioxide with their environment, essential for respiration.

Skin Burn

An injury to the skin caused by exposure to heat, chemicals, electricity, or radiation, which can vary in severity from mild to life-threatening.

Infection

The invasion and multiplication of microorganisms such as bacteria, viruses, and parasites that are not normally present within the body.