BBC Bitesize - KS3 Physics - Pressure - Revision 1
Pressure is a measure of the amount of force acting on a given amount of surface area. A quantitative, or mathematical, relationship exists between force, area. Pressure. Pressure is defined as force per unit area. It is usually more convenient to use pressure rather than force to describe the influences upon fluid behavior. Pressure and force are related, and so you can calculate one if you know the F/ A. Because pressure is force divided by area, its meter-kilogram-second (MKS).
Pressure is Force per Unit Area
Pressure equals Force divided by Area You can see that for a given force, if the surface area is smaller, the pressure will be greater. If you use a larger area, you are spreading out the force, and the pressure or force per unit area becomes smaller. Solid pressing on confined fluid When a liquid or gas is confined in a container or cylinder, you can create a pressure by applying a force with a solid piston.
The pressure created in the cylinder equals the force applied divided by the area of the piston: In a confined fluid—neglecting the effect of gravity on the fluid—the pressure is the same throughout the container, pressing equally on all the walls. In the case of a bicycle pump, the pressure created inside the pump will be transmitted through the hose into the bicycle tire.
But the air is still all confined. Pressure is in all directions in a fluid Increasing the force will increase the pressure inside the cylinder.
Pressure is Force per Unit Area by Ron Kurtus - Physics Lessons: School for Champions
Caused by gravity Since the weight of an object is a force caused by gravity, we can substitute weight in the pressure equation. Thus the pressure P caused by the weight W of an object is that weight divided by the area A where the weight is applied. Pressure equals Weight divided by Area Example with shoes A good example of how a force on small area can result in a very high pressure is seen in women's shoes with high spiked heels.
These types of shoes can cause damage to some floors due to the very high pressure on the floor at the heel.
When we take the thin side, the surface area is reduced, and so it cuts the fruit easily and quickly. This is one example of a practical application of pressure. For gases, pressure is sometimes measured not as an absolute pressure, but relative to atmospheric pressure ; such measurements are called gauge pressure.
Where space is limited, such as on pressure gaugesname platesgraph labels, and table headings, the use of a modifier in parentheses, such as "kPa gauge " or "kPa absolute ", is permitted. However, whenever equation-of-state properties, such as densities or changes in densities, must be calculated, pressures must be expressed in terms of their absolute values.
Pressure - Wikipedia
Focusing on gauge values, one might erroneously conclude the first sample had twice the density of the second one. Scalar nature[ edit ] In a static gasthe gas as a whole does not appear to move.
The individual molecules of the gas, however, are in constant random motion. Because we are dealing with an extremely large number of molecules and because the motion of the individual molecules is random in every direction, we do not detect any motion.What is Pressure in Physics with Examples & Formula - Physics Terminology Explained - SimplyInfo
If we enclose the gas within a container, we detect a pressure in the gas from the molecules colliding with the walls of our container. We can put the walls of our container anywhere inside the gas, and the force per unit area the pressure is the same.
We can shrink the size of our "container" down to a very small point becoming less true as we approach the atomic scaleand the pressure will still have a single value at that point.