Concept Summary

Batesville High School Science

PressurePressure depends on:

The applied force - more force means more pressure

The area over which the force is applied - more area means less pressure

Force moves you - pressure determines how it feels.

PressurePressure = force/areaCommon units of pressure:

English system: lbs/in2 (ppi) Metric system: 1 Newton/m2 = 1 Pascal

1 kiloPascal = 1000 Pascal

Liquid PressureThe force a liquid exerts on the bottom

of a container equals the weight of the liquid.

The pressure a liquid exerts on the bottom of a container depends only on the density of the liquid and the depth of the container.

Pressure = weight density x depth

Buoyant ForceObjects immersed in a liquid

experience an upward buoyant force.The buoyant force is due to the

difference in pressure (and force) on the top and bottom of the object.

Archimedes’ PrincipleThe buoyant force on an object equals

the weight of the liquid displaced (moved out of the way) by the object.

Sinking & Floating If you put an object into a liquid, it:

Sinks if the object is more dense than the liquid.

Floats if the object is less dense than the liquid.

Neither sinks nor floats if the object has the same density as the liquid.

Principle of FlotationA floating object displaces a weight of

liquid equal to its own weight.

Pascal’s PrincipleA change in pressure at any point in a

confined liquid is transmitted undiminished to all points and all directions of the liquid.

The End