Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
The Earth is a sphere (ball-shaped) that rotates on an imaginary line called an axis. This rotation happens from West to East.
The Sun is a star that provides light and heat. It does not move around the Earth; instead, the Earth spins on its axis.
Day occurs for the half of the Earth facing the Sun, receiving light energy. Night occurs for the half facing away, in the Earth's own shadow.
One full rotation of the Earth takes approximately hours, which we define as day.
The Sun appears to 'rise' in the East and 'set' in the West. This is an apparent motion caused by the Earth's rotation.
Shadows change throughout the day. They are longest during the early morning and late afternoon when the Sun is low in the sky, and shortest at midday ( PM) when the Sun is at its highest point.
📐Formulae
💡Examples
Problem 1:
If the Earth stopped rotating on its axis, what would happen to the cycle of day and night?
Solution:
The day and night cycle would stop.
Explanation:
Because the Earth rotates, different parts of the planet take turns facing the Sun. If rotation stopped, one side would be in permanent daylight (very hot) and the other side in permanent darkness (very cold).
Problem 2:
At what time of day would you expect a shadow cast by a stick to be the shortest: AM, PM, or PM?
Solution:
PM (Midday)
Explanation:
At PM, the Sun is at its highest point in the sky directly above the object. This causes the light rays to hit the object from a vertical angle, resulting in the shortest possible shadow.
Problem 3:
If a town experiences hours of daylight, how many hours of night will it have in a single -hour period?
Solution:
hours
Explanation:
Using the formula , we calculate .