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If you were playing dodge ball would you rather be hit with a foam ball or a bowling ball? Most of us would rather be hit by the foam ball—it would be much less painful! Although both balls are about the same size, there is a difference in their mass. Mass is the amount of matter an object contains. The bowling ball has more matter in it than the foam ball, so it has greater mass.
 
Journal Entry - Take out your science journal and copy the following chart into it.
 
Object
Mass of Object
Surface Gravity
Mercury    
Venus    
Earth    
Mars    
Jupiter    
Saturn    
Uranus    
Neptune    
Pluto    
Sun    
 
Click on the Clark Planetarium link and fill the information into the chart. Remember to look carefully and make sure the data matches the object. (The moon is in the data and not in the chart above.)
 

Now look at the information you have put in your chart. Answer these questions.

  1. Which object has the most mass?
  2. Which object has the most gravity?
  3. Which object has the least mass?
  4. Which object has the least gravity?
  5. What conclusion could you make about the relationship between mass and gravity? Use at least 3 sentences to explain.
 

QUIZ TIME

Choose which list of objects in the solar system is in the correct order of strength of gravity, with the first object having the GREATEST amount.

 
Extension Activity
 

Your Weight On Other Worlds

What is your weight if you became a solar system traveler and visited each planet and the sun?

The masses of objects and the distance between them will affect the gravitational pull. If an object is more massive, it will have stronger gravity. But beware!!! There are exceptions to this rule.

Mass and Weight? What is the difference?

Before we get into the subject of gravity and how it acts, it's important to understand the difference between weight and mass.

We often use the terms "mass" and "weight" interchangeably in our daily speech, but to an astronomer or a physicist they are completely different things. The mass of a body is a measure of how much matter it contains. An object with mass has a quality called inertia. We studied Newton’s first law in our “Keep on Movin'” activity. Mass is a measure of how much inertia an object displays.

Weight is an entirely different thing. Every object in the universe with mass attracts every other object with mass. The amount of attraction depends on the size of the masses and how far apart they are. For everyday-sized objects, this gravitational pull is very small, but the pull between a very large object, like the Earth, and another object, like you, can be easily measured. How? All you have to do is stand on a scale! Scales measure the force of attraction between you and Earth. This force of attraction between you and Earth (or any other planet) is called your weight.

Materials:

  • Weight scale – (Don’t have a scale or just plain don't want to weight yourself in front of others? Just choose a weight and then complete the table below. A great idea would be to choose a number that is easily multiplied and divided; like 100.)
  • Chart of surface gravity
  • Calculator

Procedure:

  1. Weigh yourself and record the “New Weight” for the Earth row.
  2. Multiply your weight by the surface gravity of each object.
  3. Record your new weight for each object.

Object

Surface Gravity

New Weight

Sun

28

 

Mercury

.38

 

Venus

.91

 

Earth

1

 

Mars

.38

 

Jupiter

2.53

 

Saturn

1.07

 

Uranus

.91

 

Neptune

1.16

 

Pluto

.05

 
Sun 28  
 
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Earths_moon_image

seasons_image

solar_system_image size_motion_distance_image microorganism_image Heat_light_and_sound_image

Get the plug-ins: Get Adobe Acrobat Reader , and Get Quicktime Player. (The QuickTime plug-in is needed to play sounds and movies correctly.)

Want to share photos of you or your friends doing this activity? Send it in an e-mail with the following information:

  1. The title of the activity
  2. The URL (Internet address)
  3. Your name.

Remember that no pictures can be used that show student faces or student names on it. 

Teachers should view the Teacher Site Map to relate Sci-ber text and the USOE 6th grade science core.


Updated October 24, 2008 by: Glen Westbroek

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