Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
The Earth is a sphere that rotates on an imaginary line called an axis. One full rotation takes hours, which creates the cycle of day and night.
The Earth revolves (orbits) around the Sun. This movement takes approximately days to complete one full journey.
The Moon is a natural satellite of the Earth. It orbits the Earth once every to days.
The Sun appears to rise in the East and set in the West. This is an apparent motion caused by the Earth spinning on its axis from West to East.
Shadows change length and position during the day. Shadows are longest at sunrise and sunset and shortest at PM (midday) when the Sun is at its highest point.
The Moon does not produce its own light; it reflects light from the Sun. As the Moon orbits the Earth, we see different amounts of its lit side, which we call phases.
📐Formulae
💡Examples
Problem 1:
If the Earth spins on its axis times, how many days have passed?
Solution:
days
Explanation:
Since rotation is equal to hours (or day), rotations equal days.
Problem 2:
At what time of day will a tree cast the shortest shadow?
Solution:
PM (Midday)
Explanation:
At midday, the Sun is at its highest point in the sky relative to the observer, which results in the shortest shadow length.
Problem 3:
Explain why we have leap years every years.
Solution:
full day
Explanation:
Because the Earth takes days to orbit the Sun, we add up the four quarters () every four years to make one extra day (February th).