Force, pressure and fluids : Force, pressure and fluids Physics
Introduction : Introduction Why is it easier to walk on snow wearing snowshoes?
Introduction : Introduction Let’s analyze the different forces acting when you stand on snow.
Vocabulary: : Vocabulary: Pressure: Pressure is the force per unit of area that is applied in the surface of an object.
Area: the extent of a 2 dimensional surface enclosed within a boundary. SI units of area: m2
Pascal: SI unit of pressure represented by the simbol Pa equal to a force of 1 N applied over an área of 1 m2.
Fluid: A substance that has no definite shape and the ability to flow.
Perpendicular: Intersecting at, or forming right angles.
Calculating Pressure: : Calculating Pressure: To calculate pressure we use the formula:
Calculating Pressure: : Calculating Pressure: Let’s look at the following example:
Calculating Pressure: : Calculating Pressure: Now, work on the following example:
Calculating Pressure: : Calculating Pressure: Now, let’s work on another problem in which we will combine what we have learned about density, weight and now, pressure:
We have 25 liters of whole milk in a bucket.
The density of milk, represented by the greek letter
Rho is equal to 1036.86 kg/m3 .
If the bottom of the bucket has the shape of a circle of a radius of 20 cm, what is the pressure applied by the milk on the botoom of the bucket?
Calculating Pressure: : Calculating Pressure: Now, let’s work on another problem in which we will combine what we have learned about density, weight and now, pressure:
Now, what would hapen if we place the 20 liters of milk in a taller and slimmer bucket that has a circular bottom of a 9 cm.
What would be the pressure applied by the milk on the botoom of the taller and slimmer bucket?
Fluids: : Fluids: Now, let’s talk about fluids. Lets look at this classic rock album cover by the 90’s grunge band nirvana.
Fluids: : Fluids: Fluids have a very special property: the weight of the water above a submerged object is applied over all the surface of the object. The pressure is applied perpendicualr to the surface.
Fluids: : Fluids: Atmospheric Pressure: We are all immersed in a fluid: air. Although air is not very dense, air does have weight and there is a lot of it above us.