Saturday, August 25, 2007

ADHESION

PASS THE PEPPER

MATERIALS

Cereal bowl
Pepper
Liquid dish detergent

PROCEDURE

Fill dish with water
Sprinkle some pepper on top of the water
Ask, "What do you think will happen to the
pepper if we add detergent?"
Drop several drops of detergent into the
center of the water.

EXPLANATION

Adhesion is the attractive molecular force
that holds together UNLIKE bodies in
contact. The water is pulling on the pepper
evenly from all directions. The detergent
reduces the adhesive force between the
pepper and water. The water around the
bowl's edges, untouched by the detergent,
still has its full pulling strength.

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