Pressure

Pascal's law

Hydrostathic pressure

Atmospheric pressure

Definition:

Definition:

Definition:

Definition:

pressure applied to an enclosed fluid will be transmitted without a change in magnitude to every point of the fluid and to the walls of the container.

pressure exerted by or existing within a liquid at rest with respect to adjacent bodies.

The atmospheric pressure is caused by the weight of air

Is defined as the physical force exerted on an object. The force applied is perpendicular to the surface of objects per unit area

Formula:

P= F/A

Example problem:

Calculate the pressure exerted by a brick that weights 20 N on a horizontal surface, if the contact area is 0.02 m2.

Representation:

image

DATA: A=0.02 m2 F=20N P=?

FORMULA: P=F/A

SUBSTITUTION: P=20N/0.02m2

SOLUTION: P=1,000Pa

Formula:

Example problem:

Representation:

P=Ogh

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image

Formula:

Pa= N/m2

Formula:

Representation:

Example problem:

P= Ogh

Representation:

Example problem:

image

What is the pressure exterted by the water over the bottom of a 20m 50m area, 2m deep, swimming pool? (water density: 1,000kg/m3)

DATA: A=1,000m2 h=2m O/water=1,000kg/m3 g=9.8m/s2 P=?

FORMULA: P=Ogh

SUBSTITUTION: P=(1,000 kg/m3) (9.8 m/s2) (2m)= 19,600 N/m2

SOLUTION: 19,600Pa

image

In hydraulic press, the largest piston by cross-section has an area of A1=5.0cm2. If a force of 250N is applied to the small piston, what is the magnitude of the force F2 on the largest piston?

DATA: A1=200cm2=0.02m2 A2=5.0cm2=0.0005m2 F2=250N F1=?

FORMULA: F1/A1=F2/A2

SUBSTITUTION: F1/0.02M2=250N/0.0005m2= F1=(250N)(0.02m2)/0.0005m2

SOLUTION: F1=10,000N