1. Buoyancy
E.Pere
3rd grade

2. Buoyancy is the ability of an object to float in water.

3. How do you know if an object is floating?
All or part of the object is above a liquid.

5. How do you know if an object is sinking?
This ship is on its way to the bottom of the ocean.
When no part of the object is above the surface of a liquid.

6. Archimedes is also known as The Father of Buoyancy.
Eureka!
Archimedes was a scientist and mathematician, a citizen of Greece, who lived in a city called Syracuse, in Sicily over 2,000 years ago. The most important thing about Archimedes was that he was a great thinker.
Archimedes is also known as The Father of Buoyancy.

7. Displacement and Volume
Think about how Archimedes solved the King’s crown problem.
What happened when Archimedes sat down in the bathtub?
Why did this happen?
Displacement is when one object moves out of the way for another.
Volume is the amount of space it takes up.

8. Think About the Aesop’s Fable, The Crow and the Pitcher
He knew how to use displacement!

9. How does putting an object in water affect the water level?
Remember – Archimedes said that no two objects can occupy the same space. So the water moves out of the way (displacement) when an object is put in the liquid.
But……where does the water go?
Look at the bucket after an object is placed in the liquid. The water moves out of the way and goes up the container.
Think: what would happen to the water if there were no
more room in the container?

10. What happens to the water level when you put cargo in a boat?

11. What Are Density, Volume, and Mass? Stuffing, Space, and Stuff!
Beaker of green Jello with bubbles
Beaker of green Jello
The Jell-O fills the same amount of space, or volume, in both beakers, but the left-hand beaker holds more stuff, or mass. That means it's more dense

12. Things denser than water sink. Things less dense than water float!
Volume means how much space, or room, something occupies. Mass means the amount of stuff (matter) in something. Mass is almost like weight, except for one thing: your weight varies depending on gravity, whereas your mass is constant. If you weigh 100 pounds on Earth, you'll weigh 16.6 pounds on the Moon! Density is the ratio of Mass to Volume. In other words, "how much stuff is crammed into one space?" A bucket full of marbles is more dense than a bucket of ping pong balls, because marbles have more STUFF or matter in the same amount of space. So what?
Things denser than water sink. Things less dense than water float!

13. Look on my webpage and click on video lessons to see a video about VOLUME and DENSITY and how it affects an object’s ability to float.

14. Do objects float better in salt water or fresh water?
When you put something in water, it has to push (displace) enough water to make room for its entire volume before it can sink or float. When you dissolve salt in water, you've just added more STUFF, or MASS, to the same volume of water. Saltwater weighs the weight of the water plus the weight of the salt.
Salt isn't very heavy, but it's enough to make the difference when you drop something that just barely has enough weight to sink in freshwater.

15. Why do some objects sink, and others float?
It depends on the density
of the object.
The regular coke has more sugar than the diet coke. This makes the regular coke denser than the water, so it sinks.
The density of a material is defined as its mass per unit volume.

16. How are sinking and floating different in salt water?
The egg in the salted water
floated because the egg was
less dense than the water.
The molecules in the water
were closer together and acted
like a "net" to hold up the egg.
The egg in the fresh water
sank because it was denser
than the water. The molecules
in the water were far apart.

17. The Scientific Method
The scientific method is a process for experimentation that is used to explore observations and answer questions. Scientists use the scientific method to search for cause and effect relationships in nature. In other words, they design an experiment so that changes to one item cause something else to vary in a predictable way.

18. Question Prediction Hypothesis Observations Conclusion Reflect
What do you want to find out?
Question
What do you think will happen?
Use background knowledge (schema) to help your thinking.
Prediction
Explain why you think your prediction will happen.
Hypothesis
The Scientific Method
Begin the experiment. Watch and examine closely.
record what happens
Observations
Using information from the experiment, explain what happened and why it happened.
Conclusion
Will you be able to redo the experiement?
How can you change the experiment?
Reflect

19. Buoyancy Quiz
How can objects that sink be made to float? (Think about the clay ball. How were we able to make it float?
2. Why do heavy ships float?
Why did the orange with the peel float?
4. Why did the orange without the peel sink?
5. What are the 4 properties of a good boat?
6. Why does a rock sink no matter what shape it is?