Study Spot
Customized learning paths based on interests
Air pressure is what you measure with a tire gauge. Atmospheric pressure is what you measure with a mercury barometer. Let me be more specific. Pressure is the amount of force per unit area that a gas exerts on a surface. If the pressure on both sides of the surface are equal then the relative pressure is zero. Absolute pressure is when the other side of the surface is at vacuum. So the pressure you measure with a tire gauge is really the absolute pressure inside of the tire minus the absolute atmospheric air pressure, which is measured with respect to vacuum