Density and Flotation

• Task: Given 3 eggs, salt, water, and 3 beakers, make it so that one egg sinks, one egg floats and one egg stays suspended in the middle of the water.

• Objects sink or float based upon density.

• If an object is less dense that water (p < 1g/cm3) it will float.

• If an object is more dense than water (p < 1g/cm3) it will sink.

Object Density (g/cm3) Sink or Float

Aluminum 2.7 g/cm3

Penny 7.2 g/cm3

Gold 19.3 g/cm3

Wood 0.85g/cm3

Sugar 1.6g/cm3

Ice 0.917g/cm3

Baby Oil 0.83g/cm3

Mercury 13.94g/cm3

Will a penny sink or float in liquid mercury?

Mercury Video

QUIZ: make an 8 item density column.

7 Layer Density Column

Object Density g/cm3

Honey 1.42

Light Corn Syrup 1.33

Dawn Dish Soap 1.06

Water 1.00

Vegetable Oil .92

Baby Oil .83

Rubbing Alcohol 0.79

You must use 3 solids!Hand in a labeled picture in COLOR! Bring it in for extra credit!

Objects generally sink or float based upon density. • More dense = sinks• Less dense - floats

How much of an Object will Float above Water?

Zinc

0.92g/cm3 7.13g/cm3

The zinc will sink as its denser than water

The ice floats as its less dense than water

But how much is underneath the water?

If 92% is under water then the other 8% is visible!

ICE CUBE

About 8% visible

Just the Tip of the Iceberg!!!

Photo via: Adventure-Journal

90% of this ice berg is below water (salt water)

Most of an Iceberg is below water!

Think about this and ships traveling in the

ocean.

The TITANIC

Artistic Rendition of an iceberg.

Wiki commons

Flotation Problems (Handout)

Knock on Wood

• A branch snaps and falls into a river. It has a density of 0.7g/cm3, will it sink or float and if it floats how much of it will be visible?

Floating Basketball

• A basketball has a mass of 624g and a volume of 7512cm3. What percentage of a basketball will be visible above water?

Rank each object from the most dense to the least dense:

AB

CD

E

F

Most Dense

[1][2][3][4][5][6]

Least Dense