Lesson: Orbital Mechanics Physics • 9th Grade

In this lesson, we will learn how to use the formula T = 2πr/v to calculate the orbital characteristics of a planet, moon, or man-made satellite in a circular orbit.

Lesson Plan

Objectives

Students will be able to

use to find the circumference of an orbit from its radius and vice versa,
use to find the orbital speed of an object from the radius of its orbit and its orbital period and vice versa.

Prerequisites

Students should already be familiar with

the qualitative understanding of circular orbits.

Exclusions

Students will not cover

any calculations for elliptical orbits,
any of Kepler’s laws,
Newton’s law of gravitation ,
any centripetal force or acceleration calculations and .

Lesson Video

Lesson Explainer

Sample Question Videos

06:15
06:47
07:35

Lesson Worksheet

Q1:

Two planets, A and B, orbit a star. Both planets have circular orbits. Planet A orbits the star at a distance of km and at a speed of 30 km/s. Planet B orbits the star at a distance of km and at a speed of 17 km/s.

How many times is the length of planet B’s orbit greater than planet A’s?

How many times longer does it take for planet B to orbit the star than planet A? Give your answer to 1 decimal place.

Q2:

A satellite orbits Earth at an orbital radius of 10,000 km. Its orbital period is 2.8 hours. How fast is the satellite moving? Give your answer to the nearest kilometer per second.

Q3:

Titan is the largest moon of Saturn. It has a roughly circular orbit and it orbits Saturn at a distance of 1,220,000 km with a period of 15.9 days. At what speed is Titan moving along its orbit? Give your answer to the nearest kilometer per second.