Bell-Ringers

12 June 2009

Bell-Ringer• 12 June 2009

• LT: Describe the forces acting on an object in a fluid.

In your lab group, build three different sizes of aluminum foil boats that will float in your beaker of water.

Push down on each boat with your finger -- what do you feel?

Floating forces 1

• What experiences have you had with floating objects?

Floating forces 2

• What experiences have you had with lifting sunken objects under water?

Some questions to answer…

• Do objects weigh the same in air as in the water? (Gather data to prove your point.)

• What is the weight of a block of wood in air and fully immersed in the water? (Gather data.)

• What is the weight of a piece of clay in air and suspended the water? (Gather data.)

Another question…

• If weight in the air is not the same as in water, why the difference?

• Draw the forces acting on a floating object.

Finding the “floaty” force.Weight in

the airWtair

Weight on or in the water

Wtwater

“Floaty” force?(buoyant force)

FB

Fg

Fg

FB