Introduction
Weight is a measurement of the force on a object caused by gravity trying to pull the object down, towards the center of the earth. Each planet has a different gravitational force. Mars has less gravity than Earth. Therefore if you were on Mars you would weigh less because the force of gravity wouldn't be as strong as it is here on Earth.
Does this mean you would suddenly be thinner on Mars? No. You would have the same amount of mass as you do on Earth. (Mass is the amount of stuff that makes up an object.)
So, on Mars, your mass would be the same as it is here on Earth. But your weight would be different(less) because Mars has less gravity than Earth.
Gravity is an attractive force. This doesn't mean it's pretty. What "attractive" means is that an object's gravity pulls other objects toward it. Look at the chart (see below). The Earth's gravity naturally pulls us, and everything else, toward the center of the planet, which keeps us from drifting off into space.
The Earth isn't the only thing that has gravity. In fact, every single object in the universe has gravity. The tables you're sitting at have gravity. They are pulling you towards them. You have gravity, and you are pulling the tables towards you. We can't see or feel these things happening because people and tables have a such a small mass that the effects of gravity cannot be seen.
Mass is the amount of stuff contained inside an object. It takes a lot of mass to make a lot of gravity. The Earth has a lot of mass, so it has a lot of gravity. The moon's gravity is about 1/6 the amount of the Earth's because the moon has less mass than the Earth.
So what does all this have to do with weight? Well, weight is the force on a object caused by gravity trying to pull the object down. A scale measures how much gravity your mass has. A person with more mass has more gravity, and therefore weighs more.
You've probably seen video footage of astronauts walking on the moon. They seem to float between each step. Remember that the moon has about 1/6 the amount of gravity that the Earth has? Well, if you went to the moon, you'd weigh less than you do here on Earth. Does this mean you would suddenly be thinner on the moon? Absolutely not. Your mass would be the same -- there is no less of you on the moon. But your weight is different because the moon's gravity is different.
Task
By the end of the lesson, students should be able to:
- Describe Earth’s gravity as a force that pulls objects down to the center of the Earth
- Describe how weight and mass change or remain constant
- Explain how gravity determines the weight of an object
- Demonstrate that all objects, regardless of their mass, fall to the ground at the same rate
Instructions for the Webquest.
1. Find your weight on other planets and explain the results with gravity.
2. Perform Galileo's Thought Experiment right along side with him.
3. Use notes from introduction reading to answer questions about mass vs. weight.
4. Learn a new song about mass and weight.
Process
Make sure you are following along with the handout and answering every question. You will be turning it in!
STEP 1 Click on this link ----> Galileo's Thought Experiment and read Galileo’s Games. Complete the Falling Bodies section. Did you get it correct? What happened when she dropped both cannonballs?
STEP 2 Click on this link ----> Your Weight On Other Planets and enter your weight to find your weight on other planets.
Answer the following in your notebooks.
a) Do you weigh more or less on the moon?
b) On which planet did you weigh the most?
c) On which planet did you weigh the least?
d) Out of those two planets, which has a greater pull of gravity? How do you know?
e) Make a Venn Diagram for mass and weight; Include force and gravity in both circles.
STEP 3 Visit youtube and find the song Row, Row, Row Your Boat. Once you know the tune, use it to learn the following song, Mass on the Moon. Then using what you've learned, write your own verse to the song!
If we went
To the moon
Our mass would be the same.
But if we took
A scale with us
We’d see our weight has changed.
(Row, Row
Row Your Boat
Gently down the stream
Merrily, merrily
Merrily, merrily
Life is but a dream)
Evaluation
When notebooks are checked, this assignment will be graded based on completeness, organization, and whether or not it is your best work!! It will be worth 20 points.
Conclusion
You should now be able to complete today's objectives. If you cannot do the following questions, see me! :)
- Describe Earth’s gravity as a force that pulls objects down to the center of the Earth
- Describe how weight and mass change or remain constant
- Explain how gravity determines the weight of an object
- Demonstrate that all objects, regardless of their mass, fall to the ground at the same rate
Next we will be talking about the different types of friction, like air and water resistance!
Credits
Thank you to the Mrs. Mizzi, whose webquest I borrowed from heavily, as well as all of the sites used within.
Teacher Page
Miss Samantha Williams:)