Pressure is the perpendicular force per unit area, or the Stress at a point within a confined fluid. The pressure exerted on a floor by a 42-pound box the bottom of which has an area of 84 square inches is equal to the force divided by the area over which it is exerted; i.e., it is one-half pound per square inch. The weight of the Atmosphere pushing down on each unit area of Earth’s surface constitutes Atmospheric Pressure, which at sea level is about 15 pounds per square inch. In SI units, pressure is measured in pascals; one pascal equals one newton per square metre. Atmospheric pressure is close to 100,000 pascals.
The pressure exerted by a confined gas results from the Average effect of the forces produced on the container walls by the rapid and continual bombardment of the huge number of gas Molecules. Absolute pressure of a gas or liquid is the total pressure it exerts, including the effect of atmospheric pressure. An absolute pressure of zero corresponds to empty space or a complete vacuum.
Measurement of pressures by ordinary gauges on Earth, such as a tire-pressure gauge, expresses pressure in excess of atmospheric. Thus, a tire gauge may indicate a pressure of 30 pounds (per square inch), the gauge pressure. The absolute pressure exerted by the air within the tire, including atmospheric pressure, is 45 pounds per square inch. Pressures less than atmospheric are negative gauge pressures that correspond to partial vacuums.
Atmospheric pressure
Atmospheric pressure, also called barometric pressure, force per unit area exerted by an atmospheric column (that is, the entire body of air above the specified area). Atmospheric pressure can be measured with a mercury barometer (hence the commonly used synonym barometric pressure), which indicates the height of a column of mercury that exactly balances the weight of the column of atmosphere over the barometer. Atmospheric pressure is also measured using an aneroid barometer, in which the sensing element is one or more hollow, partially evacuated, corrugated Metal disks supported against collapse by an inside or outside spring; the change in the shape of the disk with changing pressure can be recorded using a pen arm and a clock-driven revolving drum.
Atmospheric pressure is expressed in several different systems of units: millimetres (or inches) of mercury, pounds per square inch (psi), dynes per square centimetre, millibars (mb), standard atmospheres, or kilopascals. Standard sea-level pressure, by definition, equals 760 mm (29.92 inches) of mercury, 14.70 pounds per square inch, 1,013.25 × 103 dynes per square centimetre, 1,013.25 millibars, one standard atmosphere, or 101.325 kilopascals. Variations about these values are quite small; for example, the highest and lowest sea-level pressures ever recorded are 32.01 inches (in the middle of Siberia) and 25.90 inches (in a typhoon in the South Pacific). The small variations in pressure that do exist largely determine the wind and storm patterns of Earth.
Near Earth’s surface the pressure decreases with height at a rate of about 3.5 millibars for every 30 metres (100 feet). However, over cold air the decrease in pressure can be much steeper because its density is greater than warmer air. The pressure at 270,000 metres (10−6 mb) is comparable to that in the best man-made vacuum ever attained. At heights above 1,500 to 3,000 metres (5,000 to 10,000 feet), the pressure is low enough to produce mountain sickness and severe physiological problems unless careful acclimatization is undertaken.
Applications of atmospheric pressure
Drinking Straw
When drinking with a straw, one has to suck the straw. This causes the pressure in hte straw to decrease. The external atmospheric pressure, which is greater, will then act on the surface of the water in the glass, causing it to rise through the straw.
Rubber Sucker
When the rubber sucker is put onto a smooth surface, usually a glass or tiled surface, the air in the rubber sucker is forced out. This causes the space between the surface and the sucker to have low pressure. The contact between the rubber sucker and the smooth surface is airtight. The external atmospheric pressure, which is much higher, acts on the rubber sucker, pressing it securely against the wall.
Vacuum Cleaner
vacuum cleaner applies the principle of atmospheric pressure to remove dust particles. When it is switched on, the fan sucks out the air from space inside the vacuum. Space A then becomes a partial vacuum. The atmospheric pressure outside, which is greater, then forces air and dust particles into the filter bag. This traps the dust particles but allows the air to flow through an exit ath the back.
Lift Pump
A lift pump is used to pump water out of a well or to a higher level. The greatest height to which the water can be pumped is 10 m. This is equivalent to the atmospheric pressure. When the plunger is lifted, the upper valve closes and the lower valve opens. The atmospheric pressure, acting on the surface of the water, causes water to flow past valve B into the cylinder. When the plunger is pushed down, the lower valve closes and the upper valve opens. Water flows above the plunger.When the plunger is next lifted, the upper valve closes again and the lower valve opens once more. the atmospheric pressure, acting on the surface of the water, forces water past the lower valve into the cylinder. Simultaneously, the water above the plunger is lifted and flows out through the spout. This process is repeated until sufficient water is obtained.
Hydraulic pressure
Hydraulic pressure is the pressure of hydraulic fluid which it exerts in all direction of a vessel, hose or anything in which it is supposed to exert the force per unit area. This pressure is responsible to create flow in a hydraulic system as fluid flows from high pressure to low pressure. Thus energy is transferred in a hydraulic system through a fluid medium. This pressure is measured in kgf/cm sq , PSI, Bar etc.
Applications of hydraulic pressure
Hydraulic Lifts and Fluid Power
Blaise Pascal derived a law that explains how people can harness the power of fluids. When you apply pressure to liquid in a confined container, that pressure transmits equally to all other points in the container. According to the law, it’s also possible for a hydraulic system to multiply forces. For instance, a hydraulic arm uses these principles to help you hoist thousands of pounds using your hands. You press down to apply a small force to one part of the jack’s fluid, and the force multiples enough to lift a car.
Hydraulic Braking
You witness hydraulics in action every time you ride in a vehicle or see one pass; car braking systems are among the most common uses of hydraulic machines. A vehicle’s braking system has several critical components, and one of them comes in a bottle or can. Brake fluid, a hydraulic liquid, is so important that brake systems could fail without it. When you press your foot on a brake pedal, a piston and rod in a master cylinder move. This movement exerts force on hydraulic fluid constrained inside brake lines. Because of Pascal’s law, the pressure moves through the lines, presses against another cylinder and causes the vehicle’s brake shoes and pads to contact the disc or drum and slow the wheels down.
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Pressure is the force exerted per unit area. It is a fundamental quantity in physics and engineering, and it has many applications in everyday life.
Atmospheric pressure is the pressure exerted by the weight of the atmosphere above us. It is equal to about 14.7 pounds per square inch (psi) at sea level. Atmospheric pressure is what keeps us from flying off into space, and it also helps to keep our bodies hydrated.
Hydrostatic pressure is the pressure exerted by a fluid at rest. It is equal to the weight of the fluid above a given point divided by the area of that point. Hydrostatic pressure is what causes water to flow downhill, and it also helps to support the weight of buildings and other structures.
Pressure is used in many everyday applications, such as in hydraulics, pneumatics, and in the operation of machines. Hydraulics is the use of fluids to transmit power. Pneumatics is the use of compressed air to transmit power. And machines use pressure to perform a variety of tasks, such as cutting, grinding, and drilling.
Pressure is a powerful force that has many applications in our lives. It is important to understand how pressure works so that we can use it safely and effectively.
Concept of pressure
Pressure is the force exerted per unit area. It is a fundamental quantity in physics and engineering, and it has many applications in everyday life.
Pressure can be defined as the force acting perpendicular to a surface divided by the area of the surface. The SI unit of pressure is the pascal (Pa), which is equal to one newton per square meter (N/m2).
Pressure can be caused by a variety of things, including the weight of a fluid, the motion of a fluid, or the Surface Tension of a fluid.
The weight of a fluid exerts pressure on the bottom of a container. This pressure is equal to the weight of the fluid divided by the area of the bottom of the container.
The motion of a fluid also exerts pressure. This pressure is called dynamic pressure. Dynamic pressure is equal to one-half the density of the fluid times the square of the velocity of the fluid.
The surface tension of a fluid also exerts pressure. This pressure is called surface tension pressure. Surface tension pressure is equal to two times the surface tension of the fluid divided by the radius of the smallest sphere that can be formed from the fluid.
Atmospheric pressure
Atmospheric pressure is the pressure exerted by the weight of the atmosphere above us. It is equal to about 14.7 pounds per square inch (psi) at sea level. Atmospheric pressure is what keeps us from flying off into space, and it also helps to keep our bodies hydrated.
Atmospheric pressure is caused by the weight of the air above us. The air is made up of molecules, and these molecules have mass. The weight of these molecules exerts a force on the Earth’s surface. This force is what we call atmospheric pressure.
Atmospheric pressure is not the same everywhere on Earth. It is higher at sea level than it is at high altitudes. This is because there is more air above us at sea level than there is at high altitudes.
Atmospheric pressure also changes with the weather. It is higher when the weather is fair and lower when the weather is stormy. This is because the air pressure is lower when there are more clouds in the sky.
Hydrostatic pressure
Hydrostatic pressure is the pressure exerted by a fluid at rest. It is equal to the weight of the fluid above a given point divided by the area of that point. Hydrostatic pressure is what causes water to flow downhill, and it also helps to support the weight of buildings and other structures.
Hydrostatic pressure can be calculated using the following equation:
$$P = \rho g h$$
where:
- $P$ is the hydrostatic pressure
- $\rho$ is the density of the fluid
- $g$ is the acceleration due to gravity
- $h$ is the depth of the fluid
Hydrostatic pressure is important in many engineering applications. For example, it is used to design Dams and other structures that must withstand the weight of water.
Utility of pressure in daily life
Pressure is used in many everyday applications, such as in hydraulics, pneumatics, and in the operation of machines.
Hydraulics is the use of fluids to transmit power. Pneumatics is the use of compressed air to transmit power. And machines use pressure to perform a variety of tasks, such as cutting, grinding, and drilling.
Pressure is a powerful force that has many applications in our lives. It is important to understand how pressure works so that we can use it safely and effectively.
What is pressure?
Pressure is a force applied over an area. It is measured in pascals (Pa), which are equal to one newton per square meter (N/m2).
What is atmospheric pressure?
Atmospheric pressure is the pressure exerted by the weight of the atmosphere above us. It is equal to about 101,325 Pa at sea level.
What is hydrostatic pressure?
Hydrostatic pressure is the pressure exerted by a fluid at rest. It is equal to the weight of the fluid above a given point divided by the area of that point.
What are the utilities of pressure in daily life?
Pressure is used in many different ways in daily life. Some examples include:
- Keeping things in place. Pressure can be used to keep things in place, such as when you use a plunger to unclog a drain.
- Moving things. Pressure can be used to move things, such as when you use a hydraulic press to lift a heavy object.
- Generating power. Pressure can be used to generate power, such as when you use a waterwheel to generate electricity.
- Cleaning things. Pressure can be used to clean things, such as when you use a pressure washer to clean your car.
- Cooking food. Pressure can be used to cook food, such as when you use a pressure cooker to cook rice.
What are the dangers of pressure?
Pressure can be dangerous if it is not used properly. Some examples of the dangers of pressure include:
- Blast injuries. If pressure is released suddenly, it can cause a blast injury.
- Crush injuries. If pressure is applied to a body part, it can cause a crush injury.
- Decompression sickness. If pressure is reduced too quickly, it can cause decompression sickness, also known as the bends.
How can you avoid the dangers of pressure?
You can avoid the dangers of pressure by following these safety tips:
- Use the correct pressure for the job. Do not use more pressure than is necessary.
- Wear protective gear. Wear gloves, goggles, and other protective gear when working with high-pressure equipment.
- Be aware of your surroundings. Make sure that there are no people or objects in the area where you are working with high-pressure equipment.
- Follow the manufacturer’s instructions. Read and follow the manufacturer’s instructions for any high-pressure equipment that you use.
What is pressure?
(A) Force per unit area
(B) Energy per unit volume
(C) Power per unit area
(D) Acceleration per unit areaWhat is atmospheric pressure?
(A) The pressure exerted by the atmosphere on the Earth’s surface
(B) The pressure exerted by the Earth’s gravity on the atmosphere
(C) The pressure exerted by the atmosphere on objects in the atmosphere
(D) The pressure exerted by the atmosphere on objects on the Earth’s surfaceWhat is hydrostatic pressure?
(A) The pressure exerted by a fluid at rest
(B) The pressure exerted by a fluid in motion
(C) The pressure exerted by a fluid at the bottom of a container
(D) The pressure exerted by a fluid at the top of a containerWhat are some examples of the utility of pressure in daily life?
(A) The use of a pressure cooker to cook food quickly
(B) The use of a hydraulic press to lift heavy objects
(C) The use of a water gun to shoot water
(D) All of the aboveWhat are some of the dangers of high pressure?
(A) It can cause damage to the body
(B) It can cause objects to explode
(C) It can cause fires
(D) All of the aboveWhat are some of the dangers of low pressure?
(A) It can cause the body to lose fluids
(B) It can cause the body to overheat
(C) It can cause the body to suffocate
(D) All of the aboveWhat are some of the ways to prevent the dangers of high pressure?
(A) Use a pressure regulator
(B) Use a safety valve
(C) Use a pressure relief valve
(D) All of the aboveWhat are some of the ways to prevent the dangers of low pressure?
(A) Drink plenty of fluids
(B) Stay cool
(C) Avoid high altitudes
(D) All of the aboveWhat is the unit of pressure in the International System of Units (SI)?
(A) Pascal (Pa)
(B) Newton per square meter (N/m2)
(C) Kilogram per square meter (kg/m2)
(D) BarWhat is the unit of pressure in the United States customary system of units?
(A) Pound per square inch (psi)
(B) Pound per square foot (psf)
(C) Kilogram per square meter (kg/m2)
(D) Bar