Terms
Floating/Sinking
Increase or Decrease?
Fluid Pressure Principles
Odds and Ends
100

Used by submarines to change their buoyancy.

Ballast tanks

100
The upward force exerted by a fluid on a submerged object.
Buoyant Force
100
As you go deeper under water, your ears hurt because the pressure that the water exerts on you _______.
Increases
100

The equation for pressure.

Pressure  = force / area

100

This is the reason that air bubbles are spheres.

The air inside exerts an equal pressure in all directions.

200
The amount of matter in a given amount of space.
Density
200

The buoyant force makes objects appear to have less of this.

Weight

200
As your elevation increases, atmospheric pressure __________.
Decreases
200

If air flows from area B to area C, then area C must be an area of __________.

lower pressure

200
Why aren't humans crushed by the air pressure around us?
Humans have fluids in their bodies that exert pressure outwards as well. The inward push of the air and the outward push of our fluids balance.
300
An amount of Force acting on a specific amount of area.
Pressure
300
An object will sink if the Buoyant Force acting on it is ________ than the force of gravity acting on it.
Weaker
300

The equation for density.

density = mass/volume

300

What happens to pressure as you increase the area?

It decreases

300
Why can a 1000 N metal boat float when a 1000 N cube of the same metal sinks?
The shape of the boat displaces more water than the cube, which results in a stronger Buoyant force on the boat.
400

A substance whose molecules move past one-another easily and which always takes the shape of its container.

Fluid

400

The buoyant force acting on a submerged object is equal to the weight of the water it displaces.

Archimedes principle
400
People wearing snowshoes can walk without sinking because the increase in the area the shoe covers causes a _________ in pressure.
Decrease
400

The density of an object that has a volume of 20 liters and a mass of 10 kg.

0.5 kg/L

400
Why does ice float in water?
Ice expands when it freezes, meaning the same amount of mass takes up more space. Because of this, ice has a lower density than water and will float.
500

The pressure experienced at the bottom of the atmosphere and what causes atmospheric pressure.

About 14 p.s.i. caused by the weight of the atmosphere.

500

An object weighs 100 N and displaces water with a weight of 300 N. What will happen to the object if placed in water?

The object floats

500

In my demo with the water bottle and the ketchup packet, why did the ketchup packet sink when I squeezed the water bottle?

The volume of the ketchup packet was decreased, and so the amount of water it could displace also decreased (the density was increased above the density of water).

500

Why did the soda can suddenly crush in my demonstration?

The ice water caused the steam to condense, lowering the pressure below that of the surrounding air pressure.

500

Explain the formation of a tornado.

An area of extremely low pressure causes surrounding higher-pressure air to rush toward it at high speed. The air at the center of the low pressure area starts to spin, and a vortex forms. The vortex reaches the ground and causes damage.

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