Weight and Mass in SpaceWeight and Mass in Space

Have you ever thought about Have you ever thought about how much you would weigh how much you would weigh

on a different planet?on a different planet?

Well guess what….Well guess what….

……Your weight is totally different on Your weight is totally different on each of the other planets than it is each of the other planets than it is

here on Earth!here on Earth!

Here’s an example.... Here’s an example....

On Earth…On Earth…

Slugger weighs 15 pounds. Let’s pretend he Slugger weighs 15 pounds. Let’s pretend he jumped aboard a space shuttle and took a jumped aboard a space shuttle and took a

trip to each planet….trip to each planet….

On the Sun…On the Sun…

Slugger weighs 418.5 Slugger weighs 418.5 pounds!pounds!

Yikes, Slugger!! Maybe Yikes, Slugger!! Maybe we should put you on we should put you on

a diet!!a diet!!

But on the Moon… But on the Moon…

Slugger weighs only Slugger weighs only 2.55 pounds! 2.55 pounds!

On Mercury…On Mercury…

Slugger weighs 6 pounds.Slugger weighs 6 pounds.

On Venus…On Venus…

Slugger weighs 13.5 pounds.Slugger weighs 13.5 pounds.

On Mars…On Mars…Slugger weighs 5.7 pounds.Slugger weighs 5.7 pounds.

On Jupiter…On Jupiter…Slugger weighs 39.75 pounds! Slugger weighs 39.75 pounds!

On Saturn…On Saturn…

Slugger weighs 17.1 pounds.Slugger weighs 17.1 pounds.

On Uranus…On Uranus…

Slugger weighs 15.6 pounds.Slugger weighs 15.6 pounds.

Hey, that’s pretty close to how much he Hey, that’s pretty close to how much he weighs on Earth. I wonder why… Any weighs on Earth. I wonder why… Any

ideas??ideas??

On Neptune…On Neptune…

Slugger weighs 21.3 pounds.Slugger weighs 21.3 pounds.

Did anyone notice a pattern Did anyone notice a pattern between the size of the planet and between the size of the planet and

Slugger’s weight?Slugger’s weight?

Slugger Slugger weighed weighed moremore on everything on everything that was larger that was larger than Earth (Sun, than Earth (Sun, Jupiter, Saturn, Jupiter, Saturn, Uranus, and Uranus, and Neptune).Neptune).

Slugger Slugger weighed weighed lessless on everything on everything that was smaller that was smaller than Earth (moon, than Earth (moon, Mercury, Venus, Mercury, Venus, and Mars).and Mars).

Hmmm….Interesting…….

I wonder why?????

It’s all about GRAVITY…It’s all about GRAVITY…How much you weigh on a planet depends How much you weigh on a planet depends

on how much on how much gravitygravity the planet has. the planet has.

GravityGravity -the force that pulls things back -the force that pulls things back down toward the planet.down toward the planet.

All planets (plus the sun and moon) have All planets (plus the sun and moon) have gravity, but they all have different gravity, but they all have different amounts.amounts.

GRAVITYGRAVITYThe bigger the object, the more gravity it The bigger the object, the more gravity it

has….which means you weigh more on has….which means you weigh more on the bigger planets!the bigger planets!

The smaller the object, the less gravity it The smaller the object, the less gravity it has….which means you weigh less on the has….which means you weigh less on the smaller planets!smaller planets!

Don’t worry….You’ll get to calculate Don’t worry….You’ll get to calculate your weight on all the other planets your weight on all the other planets

for homework tonight. for homework tonight.

But before we do that….But before we do that….There is one more thing to learn!!There is one more thing to learn!!

MassMass

Although Slugger’s Although Slugger’s weight weight changes on each changes on each planet, his planet, his massmass does not. does not.

What is What is massmass??

MassMass MassMass is the amount of “stuff” in something. is the amount of “stuff” in something. Mass is what an object is made up of. Mass is what an object is made up of.

For example, Slugger has 4 legs on Earth. When he For example, Slugger has 4 legs on Earth. When he visits all the other planets, he will still have 4 legs, right? visits all the other planets, he will still have 4 legs, right? His mass will stay the same no matter what planet he His mass will stay the same no matter what planet he visits. Visiting another planet doesn’t affect Slugger’s visits. Visiting another planet doesn’t affect Slugger’s mass (His body won’t change shape!) mass (His body won’t change shape!)

That’s the big difference between weight and mass: An That’s the big difference between weight and mass: An object’s weight will change on the different planets object’s weight will change on the different planets (because of gravity), but the mass of the object stays the (because of gravity), but the mass of the object stays the same.same.

Turn to your neighbor….Turn to your neighbor….

And talk about the difference between And talk about the difference between weight and mass!weight and mass!

(Which one will change in space, and which (Which one will change in space, and which one won’t?) one won’t?)

Before you get your homework…Before you get your homework…

Let’s practice first by using a calculator to Let’s practice first by using a calculator to find your weight on the moon!find your weight on the moon!

1)1) Enter your weight.Enter your weight.2)2) Multiply your weight by .17 (Don’t Multiply your weight by .17 (Don’t

forget to put the decimal point first!)forget to put the decimal point first!) 3)3) Press equal….Press equal….4)4) That’s how much you weigh on the That’s how much you weigh on the

moon!moon!