SINK OR FLOAT

COPY CHART Make prediction

OBJECT PREDICT S or F ACTUAL S or F

Empty plastic jar

Water filled plastic jar

Rubber stopper

wood

Metal clip

cork

Pen cap

DEMONSTRATION

Drop a coin. An aluminum quarter into a beaker filled with water

Drop an aluminum foil ball into a beaker of water

Both are metallic and have a density of 2.7g/ml

PREDICT WHAT WILL HAPPEN?

WHY DO SOME OBJECTS FLOAT AND SOME SINK?

INSTRUCTIONAL OBJECTIVES

1. DEFINE BUOYANCY (and Archimedes Principal)

2. Explain why some objects sink while others float

3. Explain what happened to the titanic when it hit the iceberg

WHY DO SOME OBJECTS FLOAT WHILE OTHER OBJECTS SINK?The coin sinks because it weighs more than the water it

displaces. The aluminum foil ball floats because there is air trapped inside the folds. Air weighs less than water; so the ball weighs less than the water it displaces

TITANIC STORY

GUESS THE AIM??????

AIM: HOW DID THE TITANIC SINK?

SOLVE THE PHYSICS/ALGEBRA equation on the worksheet

1. How much does the object weigh in air?___

2. How much does it weigh in water?______

3. What is the apparent loss of weight in water?_____

ARCHIMEDES GREEK SCIENTIST

BUOYANCY

• Archimedes the Greek scientist discovered that –floating objects are supported by a force called BUOYANCY.

• ARCHIMEDES PRINCIPAL

• 1. the buoyant force on any object is equal to the weight of the liquid the object displaces

• 2. an object immersed in a liquid appears to lose weight, and the apparent weight loss is equal to the weight of the liquid displaced

BUOYANCY OF PERSON IN OCEAN

HOW DID ARCHIMEDES PRINCIPAL EXPLAIN HOW THE TITANIC SANK?

TAKE A FEW MINUTES AND WRITE SEVERAL

SENTENCES EXPLAINING THIS PRINCIPAL

KEY WORD: BUOYANCY

USING ARCHIMEDES PRINCIPAL EXPLAIN HOW THE TITANIC SANK?

A steel ship floats because it is constructed to have many air compartments. The Titanic sank because its air filled compartments(bulkheads) filled with water after the collision with an iceberg. The added weight of the water plus the weight of the ship became greater than the buoyant force supporting the ship, thus causing it to sink rapidly.

SUMMARY

An object sinks when the weight of the object is greater than the buoyant force that supports the object. An object floats when it weighs less than the water supporting it.

SUMMARY QUIZ

1. TRUE OR FALSE CORRECT FOR FULL CREDIT

If a boat weighs 1000 pounds and the buoyant force supporting is 800 newtons.

The boat will sink.

2. Explain why the titanic sank scientifically?

3. why does a metal anchor sink to the ocean bottom?