Definition of Pressure in Chemistry, Physics, and Engineering

Pressure is defined as a measure of the

force applied over a unit area. Pressure is

often expressed in units of Pascals (Pa),

newtons per square meter (N/m or kg/

m·s ), or pounds per square inch. Other

units include the atmosphere (atm), torr,

bar, and meters sea water (msw).

In equations, pressure is denoted by the

capital letter P or the lowercase letter p.

Pressure is a derived unit, generally

expressed according to the units of the

equation:

P = F / A

where P is pressure, F is force, and A is area

Pressure is a scalar quantity. meaning it has

a magnitude, but not a direction. This may

seem confusing since it's usually obvious

the force has direction. It may help to

consider pressure of a gas in a balloon.

There is no obvious direction of the

movement of particles in a gas. In fact, they

move in all directions such that that the net

effect appears random. If a gas is enclosed

in a balloon, pressure is detected as some

of the molecules collide with the surface of

the balloon. No matter where on the

surface you measure the pressure, it will be

the same.

Usually, pressure is a positive value.

However, negative pressure is possible.

Learn more: https://www.thoughtco.com/definition-of-...try-604613

Pressure is defined as a measure of the

force applied over a unit area. Pressure is

often expressed in units of Pascals (Pa),

newtons per square meter (N/m or kg/

m·s ), or pounds per square inch. Other

units include the atmosphere (atm), torr,

bar, and meters sea water (msw).

In equations, pressure is denoted by the

capital letter P or the lowercase letter p.

Pressure is a derived unit, generally

expressed according to the units of the

equation:

P = F / A

where P is pressure, F is force, and A is area

Pressure is a scalar quantity. meaning it has

a magnitude, but not a direction. This may

seem confusing since it's usually obvious

the force has direction. It may help to

consider pressure of a gas in a balloon.

There is no obvious direction of the

movement of particles in a gas. In fact, they

move in all directions such that that the net

effect appears random. If a gas is enclosed

in a balloon, pressure is detected as some

of the molecules collide with the surface of

the balloon. No matter where on the

surface you measure the pressure, it will be

the same.

Usually, pressure is a positive value.

However, negative pressure is possible.

Learn more: https://www.thoughtco.com/definition-of-...try-604613