Pressure | Jamb(UTME)

Jamb(utme) key points on atmospheric pressure; identify pressure measuring instrument; the use of barometer as an altimeter

Atmospheric Pressure

1. Atmospheric pressure is the force exerted by the weight of air in the Earth’s atmosphere.
2. It acts in all directions and is caused by air molecules colliding with surfaces.
3. At sea level, atmospheric pressure is about $101,325 Pa$ (pascals).
4. Atmospheric pressure decreases as altitude increases because there is less air above.
5. It plays an essential role in weather patterns and human survival.
6. Humans and other organisms have evolved to live comfortably under atmospheric pressure.
7. Variations in atmospheric pressure affect breathing and the boiling point of liquids.
8. High atmospheric pressure generally brings clear skies, while low pressure often leads to storms.
9. Atmospheric pressure is highest at sea level and decreases with height.
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Units of Pressure**==

10. Pressure is defined as force per unit area:
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    $\text{Pressure} = \frac{Force}{Area}$
11. The SI unit of pressure is the pascal (Pa).
12. One pascal is equivalent to one newton per square meter $(1Pa = 1N$/ $m^2)$.
13. Other common units of pressure include atmospheres (atm), bar, and millimeters of mercury (mmHg).
14. At sea level, 1 atmosphere (atm) equals $101,325{Pa}$.
15. 1 bar is equivalent to $100,000{Pa}$.
16. 760 mmHg equals 1 atmosphere.
17. Torr is another unit of pressure, where $1{Torr} = 1{mmHg}$.
18. Pressure in fluids is sometimes measured in pounds per square inch (psi), especially in engineering.
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Variation of Pressure with Height

19. Atmospheric pressure decreases as altitude increases because the density of air decreases.
20. At higher altitudes, there is less air pushing down, so pressure drops.
21. The decrease in pressure with height is approximately exponential.
22. At 5,500 meters above sea level, atmospheric pressure is about half of the sea-level pressure.
23. Mountaineers and pilots experience reduced atmospheric pressure, affecting oxygen availability.
24. Pressure drops faster in the lower atmosphere than at higher altitudes due to denser air near the surface.
25. This variation is the reason airplane cabins are pressurized.
26. The pressure at higher altitudes affects the boiling point of water, lowering it as pressure decreases.
27. Meteorological phenomena, such as low-pressure systems, are influenced by the vertical distribution of pressure.
28. Scientists use mathematical models to predict atmospheric pressure changes with height.
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Pressure-Measuring Instruments

29. A barometer is used to measure atmospheric pressure.
30. Mercury barometers use a column of mercury whose height changes with atmospheric pressure.
31. Aneroid barometers use a sealed metal chamber that expands or contracts with pressure changes.
32. Manometers measure the pressure of gases in closed systems.
33. A bourdon gauge is a mechanical instrument used to measure high pressures.
34. Digital pressure sensors are widely used for precise measurements in laboratories and industries.
35. Tire pressure is measured using a pressure gauge.
36. Barometers can be simple and portable, making them useful for outdoor measurements.
37. Mercury barometers are accurate but bulky and not environmentally friendly due to mercury toxicity.
38. Aneroid barometers are more portable and safer but less precise than mercury barometers.
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Use of a Barometer as an Altimeter

39. A barometer can also measure altitude by detecting changes in atmospheric pressure.
40. Since atmospheric pressure decreases with height, the barometer reading can be converted to an altitude measurement.
41. Early mountaineers and explorers used barometers to estimate the height of mountains.
42. Modern altimeters in aircraft are based on the principles of barometers.
43. Altimeters provide critical information for safe flight navigation and landing.
44. The relationship between pressure and altitude is calibrated for barometers used as altimeters.
45. Digital altimeters use pressure sensors to display altitude readings directly.
46. Weather stations located at different altitudes use barometers to record local pressure.
47. Pressure-altitude readings are adjusted for changes in temperature and local atmospheric conditions.
48. Barometers are used in hiking to estimate elevation changes during climbs.
49. The use of barometers as altimeters is vital for meteorology, aviation, and outdoor sports.
50. By interpreting barometric pressure changes, pilots can determine their height above sea level.
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Jamb(utme) key points on pressure in liquid; the relationship between pressure, depth and density; application of pressure in liquid

Pressure in Liquid

1. Pressure in liquids is the force exerted per unit area by a liquid on the walls of its container or objects submerged in it.
2. Liquids exert pressure in all directions due to the movement of their molecules.
3. The deeper you go into a liquid, the greater the pressure.
4. The formula for pressure in a liquid is:
   
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   $P = h \rho g$ where:
   • $P$ = Pressure,
   • $h$ = Depth of the liquid,
   • $\rho$ = Density of the liquid,
   • $g$ = Acceleration due to gravity $(9.8m/s^2 )$
5. Liquid pressure increases linearly with depth because the weight of the liquid above adds to the pressure.
6. At any given depth, the pressure in a liquid is the same in all directions.
7. Liquid pressure does not depend on the shape or width of the container—only on depth and density.
8. Even a small amount of liquid can exert significant pressure at great depths.
9. Atmospheric pressure acts on the surface of the liquid and adds to the total pressure inside the liquid.
10. Liquid pressure is why dams are built thicker at the base to withstand higher pressure.
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Relationship Between Pressure, Depth, and Density

11. Pressure in a liquid is directly proportional to its depth: deeper levels experience more pressure.
12. Pressure is also directly proportional to the density of the liquid: denser liquids exert more pressure.
13. Increasing the depth by doubling it will double the pressure at that point.
14. A denser liquid like mercury exerts more pressure than a less dense liquid like water at the same depth.
15. For liquids of equal depth, a higher-density liquid will exert greater pressure.
16. Pressure is independent of the surface area or volume of the liquid.
17. At zero depth (the liquid’s surface), the pressure equals atmospheric pressure.
18. The pressure at a depth in a liquid is the sum of atmospheric pressure and the liquid pressure.
19. Submarines are designed to withstand the enormous pressure that increases with depth in seawater.
20. Divers must account for changes in pressure due to depth to avoid conditions like decompression sickness.
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Transmission of Pressure in Liquids

21. Liquids are virtually incompressible, meaning they transmit pressure equally in all directions.
22. This principle is described by Pascal’s Law, which states:
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    Pressure applied to a confined liquid is transmitted equally in all directions
23. If you press on a liquid in a closed container, the pressure increases uniformly throughout the liquid.
24. Pascal’s Law is the basis for hydraulic systems.
25. Liquids transmit pressure without a significant loss of force, making them useful in various applications.
26. A force applied to a small area results in an amplified force over a larger area, as seen in hydraulic lifts.
27. The transmission of pressure allows brakes in vehicles to work effectively.
28. Pressure in liquids is not affected by the orientation of the container.
29. Hydraulic systems work because the liquid transmits pressure equally, regardless of the shape of the system.
30. Pascal's Law is used to create devices that multiply force, like jacks and presses.
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Applications of Pressure in Liquids

31. Hydraulic systems use liquid pressure to perform work, such as lifting heavy objects.
32. Car brakes operate using hydraulic fluid to transmit pressure from the brake pedal to the wheels.
33. Hydraulic presses amplify force to mold or press objects.
34. Hydraulic jacks are used to lift cars and other heavy machinery.
35. Liquid pressure is used in water supply systems to deliver water to homes and buildings.
36. In dams, pressure from water at the base is used to generate electricity in hydroelectric power plants.
37. Liquid pressure is used in pressure gauges to measure the pressure of fluids in tanks or pipes.
38. Syringes rely on liquid pressure to push medicine into the body.
39. Submarines and deep-sea equipment are designed to withstand high liquid pressure at great depths.
40. In oil and gas industries, pressure is used to extract fluids from deep underground.
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Real-Life Examples and Importance

41. Water towers store water at a height, using liquid pressure to supply water without pumps.
42. Pressure cookers use the principle of pressure to cook food faster by raising the boiling point of water.
43. Scuba divers use pressure regulators to balance the pressure difference between the water and their breathing apparatus.
44. The shape of dams is designed to handle the increasing liquid pressure with depth.
45. Barometers measure atmospheric pressure using a liquid column, often mercury.
46. The design of ships and boats considers liquid pressure to ensure they float and remain stable.
47. Hydraulic systems are used in airplane landing gears to absorb shock during landing.
48. The principle of liquid pressure is used in irrigation systems to distribute water evenly.
49. Pressure in liquids ensures that fuel is delivered to engines in cars and planes.
50. The transmission of liquid pressure makes modern machinery and tools more efficient and powerful.
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