Pressure - Fluid statics | Basic Physics for IIT JAM PDF Download

F=P/A.
Here, the pressure P is given, as is the area of the end of the cylinder A , given by A = πr². Thus,

Discussion
Wow! No wonder the tank must be strong. Since we found F=PA, we see that the force exerted by a pressure is directly proportional to the area acted upon as well as the pressure itself.
The force exerted on the end of the tank is perpendicular to its inside surface. This direction is because the force is exerted by a static or stationary fluid. We have already seen that fluids cannot withstand shearing (sideways) forces; they cannot exert shearing forces, either. Fluid pressure has no direction, being a scalar quantity. The forces due to pressure have well-defined directions: they are always exerted perpendicular to any surface. Finally, note that pressure is exerted on all surfaces. Swimmers, as well as the tire, feel pressure on all sides.
Pressure inside this tire exerts forces perpendicular to all surfaces it contacts. The arrows give representative directions and magnitudes of the forces exerted at various points. Note that static fluids do not exert shearing forces.

Pressure is exerted on all sides of this swimmer, since the water would flow into the space he occupies if he were not there. The arrows represent the directions and magnitudes of the forces exerted at various points on the swimmer. Note that the forces are larger underneath, due to greater depth, giving a net upward or buoyant force that is balanced by the weight of the swimmer.

Section Summary

1. Pressure is the force per unit perpendicular area over which the force is applied. In equation form, pressure is defined as P = F/A
2. The SI unit of pressure is pascal and 1Pa = 1 N/m²

Conceptual Questions
How is pressure related to the sharpness of a knife and its ability to cut?
Why does a dull hypodermic needle hurt more than a sharp one?
The outward force on one end of an air tank was calculated. How is this force balanced? (The tank does not accelerate, so the force must be balanced.)
Why is force exerted by static fluids always perpendicular to a surface?
In a remote location near the North Pole, an iceberg floats in a lake. Next to the lake (assume it is not frozen) sits a comparably sized glacier sitting on land. If both chunks of ice should melt due to rising global temperatures (and the melted ice all goes into the lake), which ice chunk would give the greatest increase in the level of the lake water, if any?
How do jogging on soft ground and wearing padded shoes reduce the pressures to which the feet and legs are subjected?
Toe dancing (as in ballet) is much harder on toes than normal dancing or walking. Explain in terms of pressure.
How do you convert pressure units like millimeters of mercury, centimeters of water, and inches of mercury into units like newtons per meter squared without resorting to a table of pressure conversion factors?
Problems & Exercises
As a woman walks, her entire weight is momentarily placed on one heel of her high-heeled shoes. Calculate the pressure exerted on the floor by the heel if it has an area of  and the woman’s mass is 55.0 kg. Express the pressure in Pa. (In the early days of commercial flight, women were not allowed to wear high-heeled shoes because aircraft floors were too thin to withstand such large pressures.)
; or
The pressure exerted by a phonograph needle on a record is surprisingly large. If the equivalent of 1.00 g is supported by a needle, the tip of which is a circle 0.200 mm in radius, what pressure is exerted on the record in ?
Nail tips exert tremendous pressures when they are hit by hammers because they exert a large force over a small area. What force must be exerted on a nail with a circular tip of 1.00 mm diameter to create a pressure of (This high pressure is possible because the hammer striking the nail is brought to rest in such a short distance.)