Engage: Is the Moon Falling or Not?

You have heard the word gravity before. You also learned that Earth’s gravity pulls any object toward it even without touching it. If this is the case, then why is the Moon not falling down toward Earth? Take a few moments to watch this video.

-Why doesn't the moon fall down-- (Ask an Astronomer).mp4

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Source: 
http://houstonpbs.pbslearningmedia.org

Explore: Variables of Gravity

Gravitational attraction exists between objects with masses. In this activity, you will use the Gravity Force Lab simulation to explore the variables that affect the gravitational attraction between two objects.

Download the Variables of Gravity activity sheet from the Related Documents. You will complete this activity sheet as you investigate the variables that affect the gravitational force between the two spheres.

Make sure you have Java installed in your computer for the simulation to run.
Click on the picture below to start the simulation.
When it asks, “Do you want to run this application?” click Run.

Gravity Force Lab
Click to Run
Source: 
http://phet.colorado.edu/en/simulation/grace-labvity-for

Explain: Gravity and You

Did you know that when an object falls toward Earth, the Earth falls up to meet the falling object? Watch this video to learn more about gravitational force (gravitational attraction).

How to think about gravity - Jon Bergmann (1).mp4

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Source: 
Bergmann, Jon (Designer).(2012). How to think about gravity?[Video File] Retrieved from: http://ed.ted.com/lessons/jon-bergmann-how-to-think-about-gravity

Now that you’ve watched the video, answer the following questions in your science notebook.

  1. What happens when a rock falls from a cliff?
  2. Explain why astronauts weigh less on the Moon than they do on Earth.
  3. What will happen if the Moon increases in size? How about if it decreases in size? Explain your answer.
  4. In your own words, how would you define gravitational force?

Elaborate: Gravitationally Attracted

In this activity, you will use the same Gravity Force Lab simulation you used during the Explore part of this lesson.

Download the Gravitationally Attracted activity sheet from the Related Documents. You will complete this activity sheet as you investigate gravitational force between the two spheres in the Gravity Force Lab simulation.

Make sure you have Java installed in your computer for the simulation to run.
Click on the picture below to start the simulation.
When it asks, “Do you want to run this application?” click Run.

Gravity Force Lab
Click to Run
Source: 
http://phet.colorado.edu/en/simulation/gravity-force-lab

Evaluate: Gravitational Force Quiz

Teacher Notes

This resource is a collection of interactive materials, videos, and other digital media assembled in a conceptually scaffolded 5E lesson format. It provides alternative or additional tier-one learning options for students learning about gravitational attraction between objects—IPC (4)(F). The assignments require student participation with self-checked and teacher-checked formative assessment opportunities. For example, after students record observations and data in their science notebooks, they may be prompted to be prepared to share their answers with the class. Review the resource before assigning it to your students. Check your students to assess whether they have the prerequisite knowledge necessary to complete this lesson. Also plan for how to differentiate the assignments to meet the needs of all students.  Finally, plan follow-up review and assessment as necessary. Students will need a science notebook or something on which they may record their responses.

  Resource Map

 5E CYCLE ACTIVITY TITLE STUDENT OUTCOME FOLLOW-UP
 ENGAGE Is the Moon Falling or Not? Students will be able to explain why the Moon does not fall to Earth. Check students’ understanding of the Moon’s movement.
EXPLORE Variables of Gravity Students will be able to identify and describe the variables of gravitational force. Check students’ responses on their activity sheets.
EXPLAIN Gravity and You Students will be able to describe how gravitational forces work between two objects. Check students’ responses to the questions.
ELABORATE Gravitationally Attracted Students will be able to complete the data tables in their activity sheet. Check students’ responses to the data tables and questions.
EVALUATE Gravitational Force Quiz Students will be able to complete the gravitational force quiz. Student self-check.

 

Critical Vocabulary

Mass
Weight
Distance
Force
Gravitational Force
Gravity

Answer Key 

Engage     Not applicable
Explore
  1. In this simulation, the dependent variable is the force (gravitational force).
  2. In this simulation the independent variables are the masses of the spheres and the distance between the two spheres.
  3. The arrow above each sphere represents the amount of gravitational force. The longer the arrow, the greater the force; the shorter the arrow, the smaller the force.
  4. You can change the gravitational force between the two spheres by changing their masses and changing the distance between them. 
Explain
  1. The rock falls down toward Earth, and Earth falls up toward the rock.
  2. Because the Moon is less massive than Earth, the gravitational force between the astronaut and the Moon is smaller, making the astronaut weigh less on the Moon.
  3. If the Moon increased in size and its velocity remained constant, it could fall toward Earth. If the Moon decreased in size and maintained its velocity, it could fly into outer space.
  4. Answers may vary.
Elaborate

Date Table 1 

Force on m2 by m1 Force on m1 by m2

Answers

  1. When the masses of the two spheres were increased, the gravitational force increased.
  2. When the distance between the two spheres increased, the gravitational force decreased.
  3. I can infer that the gravitational force between two objects is directly proportional to their masses but inversely proportional to the distance between them.
  4. The gravitational force exerted by Earth on my body is equal to the gravitational force exerted by my body on Earth. However, because of the big difference between my mass and Earth’s mass, it seems like I am not exerting as much gravitational force toward the Earth.
     
Evaluate
  1. A
  2. B
  3. C
  4. directly, inversely