Capture 9.PNG

# Pressure and its Unit Why is a theater seat much more comfortable than a bicycle seat? One of the main reasons any seat is comfortable is the pressure it exerts on your body. ## Pressure The comfort of the plush theater seats, shown in the image, is related to the pressure — the result of a for...

# Pressure and its Unit Why is a theater seat much more comfortable than a bicycle seat? One of the main reasons any seat is comfortable is the pressure it exerts on your body. ## Pressure The comfort of the plush theater seats, shown in the image, is related to the pressure — the result of a force distributed over an area. A theater seat's large padded and back offer a large area to support your weight than a bicycle seat does. Thus, the theater seat exerts less pressure on you and is more comfortable than the bicycle seat. Many other everyday situations also involve pressure. A sharp pencil easily pokes a hole through a sheet of paper, whereas the eraser end of the pencil does not. Why is this? The reason is the same — pressure. The pencil point has a much smaller area than the eraser, so it exerts much greater pressure than the eraser. The greater pressure exerted by the pencil point allows it to pierce the paper easily. To calculate pressure, divide the force by the area over which the force acts. So, the pressure represents the force in the unit of area. **Pressure =** $P = \frac{Force}{Area}$ In this formula, force should be in newtons (N) and area should be in square meters (m2). The resulting unit, newtons per meter square (N/m2), is the SI unit of pressure, also known as pascal (Pa). The pascal is named for French scientist Blaise Pascal. Pressures are often stated in units of kilopascals (kPa). Note that 1 kPa is 1000 Pa.