 List some applications in technology that are related to floating and sinking…

SWBAT:  Determine the density of several objects.  Define Archimedes’ principle and apply it to real world situations  Retell the story of Archimedes  Observe objects exert pressure on water and define buoyancy (positive, neutral and negative)

Groups of 6 Pick a captain, Co-captain

 Please list different types of boats:  What are they used for?  How are they different?  What materials are used to make them?

 Take 2 minutes and write down why these are important!  For this unit of study, we need to be meticulous about keeping notes!

 What causes things to float and others to sink?

 Archimedes Principle Born about 287 BC Buoyant force (upward force) is equal to the weight of the fluid displaced by the object.

 One day, while getting into his bath he noticed water spilling over the sides. In a flash, Archimedes realized the relation between the water that had fallen out and the weight of his body - in other words he discovered why some objects float and some sink! Archimedes was so excited with his discovery that he hopped out of the bath, and rushed naked into the street yelling triumphantly, 'Eureka!' 'Eureka!' (Greek word for 'I have found it!).

 Once upon a time (the 3rd century B.C.) there was a very wealthy king. Like most kings, Hiero of Syracuse (on the island of modern day Sicily) wore a crown as a symbol of his authority.  Over the years, Hiero was made aware that his Royal Goldsmith (who made his crown from Hiero � s treasury) was living a lifestyle that was beyond his means. Hiero suspected that the Royal Goldsmith was using royal gold, intended for the royal crown, to augment his personal wealth.  The goldsmith was rumored to be preparing the crowns with a cheaper alloy (using a silver-gold mix) than pure gold. No one using 3rd century B.C. technology knew how to prove or disprove the speculation that the Royal Goldsmith was � stealing from the crown

What do we now know about floating and sinking? What is the Archimedes Principle?

 Colombian sub: osM osM  Duct tape boat: qYLU qYLU

 What are some misconceptions about floating and sinking?  How did Archimedes solve the problem that was given to him by the king?

 SWBAT:  Determine the density of several objects.  Define Archimedes’ principle and apply it to real world situations  Retell the story of Archimedes  Observe objects exert pressure on water and define buoyancy (positive, neutral and negative)

 What will happen when the two cans are placed in the tank of water?

 A canoe made out of concrete – how is that possible?

BUT HOW?

 Different materials have different densities. For example: Water = 1 g/cm 3 Air = less than 1 g/cm 3 Glass = 2.5 g/cm 3 Aluminum = 2.7 g/cm 3 Steel = 7.0 g/cm 3 Concrete = varies (based on mixture) BUT THAT’S NOT ALL!

 Density is the thickness of something  Water is pushing on the object  Weight determines if an object will sink/float  Heavy objects always sink/ light ones float  The amount of water will cause objects to float or sink better

 Materials needed:  Scale  Graduated cylinder (per group)  10 different objects that fit in cylinder  Large beaker of water

 Mass objects (weight on scale)  Record the volume by placing the objects in the graduated cylinder and measuring the displaced water  Place objects in the beaker to see if it sinks of floats  Calculate the density of each object  Answer all 7 questions + conclusion!

 What is buoyancy?  What is neutral buoyancy?  Why is all this important?

SWBAT:  Create a flinker!  Observe objects exert pressure on water and define buoyancy (positive, neutral and negative)  Critique the buoyancy video clip

Solid Concrete Block Concrete Canoe Solid Steel BlockBoat made of steel

 Bill Nye - Buoyancy

 Packing peanut sinking/floating!  Please read the handout and figure out how to make something “flink”

You can shape a boat in such a way that the weight of the boat has been displaced before the boat is completely underwater by making it bigger (increasing the volume). Also, if air is trapped inside, that helps it float too! Try and figure out what shape boat is the best for holding the most mass.

 What is buoyancy?  What is neutral buoyancy?  Why is all this important?

 Here we have a toy submarine floating in a bathtub. It's a really fancy sub, made out of steel. The sub weighs one pound. When completely submerged, it displaces two pounds of water. What could you do to cause the sub to sink to the bottom of the tub? 1. Add one pound of sand to the sub's interior. Add one pound of sand to the sub's interior. 2. Add one pound of sand to the sub's interior, plus a little more. Add one pound of sand to the sub's interior, plus a little more. 3. Nothing. Since the boat displaces more water than it weighs, it's already on its way down. Nothing. Since the boat displaces more water than it weighs, it's already on its way down.

 The sub needs to weigh more than the maximum weight it can displace. You'd need to slightly more than 1 lb. of weight so that the sub weighs just over 2 lbs.

SWBAT:  Create a floating sub/Experiment with effervescent CO2  Observe objects exert pressure on water and define buoyancy (positive, neutral and negative)  Critique the buoyancy video clip #3

 Effervescent tablets include CO2 (we can test this).  How can we harness this “power”?

 What makes submarines go up and down while in the water?

 In today’s lab, you will construct a miniature submarine in groups.  You will experiment with pennies, the amount of water in the submarine and lid positions.  The submarine needs to sink to the bottom, stay down for at least 10 seconds, and then rise back up to the surface.

 Different substances have different densities.  If a substance is placed in water and it floats, this means the substance is less dense than water.  If the substance sinks, then it is denser than water. Even gases have density.

 To sink, submarines take water into their ballast tanks, causing the sub to become more dense than water.  To rise, they expel water from their ballast tanks, making the sub less dense than water.  Effervesce-(verb) to emit small bubbles as gas comes out of a liquid

This activity is designed to:  Use scientific methods to design a submarine.  Apply what you have learned about buoyancy and density.

 Buoyant forces from a fluid allows objects to float in it.  Archimedes’ Principle relates the weight of the object to the buoyant force of the fluid (in this case, water).  Density of an object changes when a gas replaces water in the film canister.

 1 Agar container  Graduated cylinder  Effervescent tablets  Pennies

1. Add pennies into the canister until it sinks for at least 10 seconds. 2. Fill the Agar container with water, drop in a tablet and quickly replace the lid. 3. Quickly drop the container into the graduated cylinder that is full of water. 4. Wait until the container stops coming up to the surface. 5. Record your results.

 Why does the submarine containing pennies and water sink?  What makes the submarine float back to the surface?  Does a water filled submarine containing no pennies sink or float?  What gas is produced by the reaction of the effervescent tablets?

 The submarine uses changes in density to cause it to sink and then float.  When the agar container is filled with water, the additional pennies make the density greater than the density of water. This causes the agar container to sink.  The effervescent tablet reacts with the water to produce carbon dioxide gas.  The gas pushes out the water in the agar container only when the hole is down, when the hole is up- the gas escapes but doesn’t push the water out.

 When all the water is gone (so that the inside of the agar container contains gas and pennies), the agar container will rise only if there are not too many pennies in it.  Now the density of the agar container is less than the density of water causing the agar container to float.

 What did we explore yesterday?  What are the purposes of these exercises?

SWBAT:  Build a boat with the greatest buoyant force possible.  Observe objects exert pressure on water and define buoyancy (positive, neutral and negative)  Critique the buoyancy video clip #3

 A girl sits in a boat floating in a pool. She picks up a rock in the boat and tosses it in the pool. The rock sinks to the bottom. No water leaves the pool from the splash the rock makes. Does the pool's water level rise, lower or stay the same?

 The water level lowers. When the rock is in the boat, it displaces its total weight. So, if the rock weighs 2 lbs., the boat is 2 lbs. heavier. When the rock is sitting at the bottom of the pool, it displaces its volume. The rock displaces more water when it's in the boat than when it's in the water, so the water level lowers when the rock is in the water.

 Bill Nye - Buoyancy

 You will use: Aluminum foil (12” x 6”) – 3 pieces (2 practice and 1 final) Tape Scissors  The goal is to build a boat with the greatest buoyant force possible. The boats will be tested by floating the boat and adding mass; the boat that supports the greatest payload wins.

 Successful Aluminum foil Boat Builders… Maximized the volume of her boat with the surface area of tinfoil she was allowed to use. A sphere has the largest volume for the smallest surface area, so the boat was most likely somewhat sphere-like. Why aren’t real boats sphere-like? They need to be able to cut through the water without creating too much friction.