Question

Which of the following was not a mechanism for the early heating of the Earth?

1) striking of the Earth by planetesimals
2) compression as the Earth contracted due to the force of gravity
3) more intense radiation coming from the sun
4) radioactive decay of the elements uranium, thorium, and potassium
5) sinking of iron toward the Earth's core

Answer 1

The mechanism that did not contribute to the early heating of the Earth was more intense radiation coming from the sun. The primary mechanisms for the early heating of the Earth include striking of the Earth by planetesimals, compression as the Earth contracted due to the force of gravity, radioactive decay of elements like uranium and potassium, and sinking of iron toward the Earth's core.

Step-by-step explanation:

The mechanism that was not responsible for the early heating of the Earth is more intense radiation coming from the sun.

The early heating of the Earth was primarily due to several factors, including:

1. Striking of the Earth by planetesimals: Every incoming planetesimal accelerated by the gravity of the protoplanet, striking with enough energy to melt both the projectile and a part of the impact area.
2. Compression as the Earth contracted due to the force of gravity: The contraction generated heat and caused the core and mantle to become hotter.
3. Radioactive decay of the elements uranium, thorium, and potassium: Primordial radioactive nuclides, such as uranium and potassium, have half-lives similar to or longer than the age of the Earth, and their decay still contributes energy to the Earth's interior.
4. Sinking of iron toward the Earth's core: This process, known as planetary differentiation, caused heavier metals to sink toward the Earth's core and release heat.