Science Olympiad Dynamic Planet Practice Test

What is the primary cause of tidal friction on Earth, contributing about 10% of the heat?

1. The Sun

2. The Moon

3. Ocean currents

4. The Earth's rotation

The correct answer is: The Moon

The primary cause of tidal friction on Earth, which contributes about 10% of the heat within our planet, is the gravitational influence of the Moon. Tidal friction occurs due to the gravitational pull that the Moon exerts on Earth's oceans, causing the water to bulge. This bulging creates tides, which result in water moving back and forth as the Earth rotates. As these tidal waters move, they experience friction with the ocean floor, as well as internal friction within the water itself. This friction generates heat, which contributes to the overall thermal energy of the Earth. While the Sun also exerts a gravitational pull on Earth and contributes to tides, its effect is less significant than that of the Moon. The Earth’s rotation and ocean currents play roles in influencing tidal patterns and water dynamics, but they do not directly contribute to tidal friction in the same way that the Moon’s gravitational pull does.