The Extraordinary Properties of Water

Cohesion•Attraction between particles of the same substance

- why water is attracted to itself

Results in:Surface tension (a measure of the strength of water’s surface) •surface film on water

-allows insects to walk on the surface of water

Water: Cohesion • Water bugs walk on water • Drops of water on a penny • Bottles don’t overflow immediately• Water “beads” on newly a waxed car

How will this affect your boat?

Cohesive Water molecules will stick together to create surface tension. Therefore - Cardboard should float on the water.

• ALSO:::: Cardboard has a lower DENSITY level than water Objects with less density than water - -- FLOATObjects with more density than water - -- SINK

Density = mass / volume

Adhesion•Attraction between two different substances

- water will bond with other surfaces such as glass, soil, plant tissues, and cotton.

Adhesion results in: Capillary action- Occurs because water is “sticky”.

It’s the flow of liquids through-out a substance - can defy gravity

Capillary Action

- allows water to move through the roots of plants

- allows blood to flow through the tiny vessels in our bodies.

- explains how water moves into a paper towel when cleaning up a spill

How will this affect your boat?

Adhesion• The water molecules

will be attracted to the cardboard and ‘stick’ to it.

Capillary Action • However, because of

capillary action, water will eventually move into the cardboard – hopefully very slowly!!

FIND THE BOAT’S CENTER OF GRAVITY

One last important bit of information!!!

11

A BOAT in water is like a see saw

100 Lbs

C G

BALANCED

100 Lbs

C G

100 Lbs

BALANCED

100 Lbs

NOT BALANCED – WILL SINK

C G

100 Lbs

NOT BALANCED – WILL SINK

C G

12

A BOAT in water is like a see saw

BALANCED

50 lbs

C G

NOT BALANCED

50 lbs

C G

NOT BALANCED

50 lbs

C G

BALANCED

50 lbs

C G

50 lbs