newtons
In the equation for pressure, force is expressed in newtons N and area is expressed in square meters m 2 . Therefore, pressure is expressed in N/m 2 , which is the SI unit for pressure. This unit is also called the pascal Pa . It is named for the scientist Blaise Pascal, whose discovery about pressure in fluids is described later in this lesson. Pressure may also be expressed in the kilopascal kPa , which equals 1000 pascals. For example, the correct air pressure inside a mountain bike tire is usually about 200 kPa.