Chapter 14 Section 2 Buoyant Force Buoyant Force

Chapter 14, Section 2 Buoyant Force

Buoyant Force • The upward force that fluids exert on all matter.

What causes it? • Fluids exerts pressure on all sides of an object. • There is more pressure on the bottom because pressure increases with depth. • The water exerts a net upward force.

Archimede’s Principle • The buoyant force on an object in fluid is an upward force equal to the weight of the fluid that the object displaces.

Weight - Sink or Float? ? • If an object’s weight is greater than the buoyant force = sinks. • If an objects weight is equal or less than the buoyant force = floats •

Buoying Up • Buoyed up means to push back up. • A duck’s weight is = to 9 N. If it dives underwater, The duck will displace more than 9 N of water. What will happen to the duck? • Answer: 9 N

Density - Sink or Float? • If an object’s density is less than the density of water = floats. • If an object’s density is greater than the density of water = sinks.

Steel Ships • Steel is 8 times more dense than water, so how do steel ships float? • They’re shaped like a bowl to increase the volume of the ship and decrease its overall density.

More Dense Than Air • Most substances are more dense than air. • They contain more mass than an equal volume of air does. • So a rubber duck doesn’t float in air, but helium balloons do.

End of Ch. 7 -2