Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
The Earth is a spherical planet that rotates on an imaginary line called its axis, which runs from the North Pole to the South Pole.
Earth rotates from West to East. This causes the Sun, Moon, and stars to appear to rise in the East and set in the West.
One full rotation of the Earth on its axis takes approximately hours ( day).
The side of the Earth facing the Sun experiences daytime, receiving light and heat energy.
The side of the Earth facing away from the Sun experiences nighttime, as it is in the Earth's own shadow.
The Earth's axis is not perfectly vertical; it is tilted at an angle of approximately .
Shadows change throughout the day because of the Earth's rotation. They are longest in the early morning and late afternoon when the Sun is low in the sky, and shortest at noon () when the Sun is at its highest point.
📐Formulae
💡Examples
Problem 1:
If the Sun is directly overhead at , describe the length of the shadow of a vertical stick compared to its length at .
Solution:
The shadow at will be much shorter than at .
Explanation:
At (noon), the Sun is at its highest point in the sky, causing the light rays to hit the object from directly above, resulting in the shortest possible shadow. At , the Sun is lower in the sky, hitting the object at a sharper angle and creating a longer shadow.
Problem 2:
Calculate how many degrees the Earth rotates in hours.
Solution:
Explanation:
Since the Earth rotates in hours, it rotates in hour (). Therefore, in hours, it rotates .
Problem 3:
Why does the Sun appear to move across the sky even though it is the Earth that is moving?
Solution:
Apparent Motion due to rotation.
Explanation:
This is similar to being on a spinning carousel; objects outside seem to move past you. Because the Earth rotates from West to East, the Sun appears to move in the opposite direction (East to West).