Module 4 Lesson 2

Module 4—Gravitational Force

Lesson 2—Newton's Law of Universal Gravitation

Get Focused

A photograph shows the International Space Station.

The International Space Station (ISS) is a research facility and joint project of five space agencies including the Canadian Space Agency. The station continues to be constructed in orbit and has been continually occupied by humans since the first crew arrived on November 2, 2000. It is also an artificial satellite, held in orbit by Earth’s gravitational field.

This is the same field that keeps smaller pieces of “space junk” in orbit—in addition to much, much larger objects such as the Moon. Considering this, what do the Moon, space junk, and the ISS have in common? Why are they all attracted to Earth in a similar, universal way?

Evidence of gravitational fields is common throughout the universe. For example, objects on the surface of Earth fall to the ground if they are not supported. Satellites and moons orbit their respective planets. In our solar system, all the planets orbit the Sun. In deep space it is possible to see stars pulling on and orbiting one another within a region of influence. Mass is common in all of these examples. For this reason, a gravitational force is often referred to as a mass-attracting force. It is one of the fundamental forces in nature and exists between any two masses. Understanding this force can help you understand why objects accelerate at the rate they do. For example, a falling apple, the International Space Station, and the Moon are all influenced by Earth’s gravitational field. Therefore, they are all accelerating. But do they accelerate at the same rate? Is the Moon falling just like the apple? Is the space station falling too?

In this lesson and related lab activities you will explore the following questions:

How does gravity affect planets, moons, and other objects in the solar system?
What does the law of universal gravitation tell you about gravity?
Is the force of gravity a constant?

Module 4: Lesson 2 Assignments

Your teacher-marked Module 4: Lesson 2 Assignment requires you to submit a response to the following:

Lab—LAB 1, LAB 2, and LAB 3
Try This—TR 1, TR 2, TR 3, and TR 4
Reflect and Connect

You must decide what to do with the questions that are not marked by the teacher.

Remember that these questions provide you with the practice and feedback that you need to successfully complete this course. You should respond to all the questions and place those answers in your course folder.

Watch and Listen

View the Law of Universal Gravitation video about Newton’s law of gravitation for the universe.