Pressure in Liquids














Pressure in Liquids : āϤ⧰āϞāϤ āϚāĻžāĻĒ : Pressure in liquids is the force exerted by a liquid per unit area. āϤ⧰āϞāϤ āϚāĻžāĻĒ āĻšā§ˆāϛ⧇ āϤ⧰āϞ⧇ āĻāĻ•āĻ• āĻ•ā§āώ⧇āĻ¤ā§ā§°āĻĢāϞāϤ āĻĒā§ā§°āϝāĻŧā§‹āĻ— āϕ⧰āĻž āĻŦāϞāĨ¤


Important Properties of Liquid Pressure āϤ⧰āϞ āϚāĻžāĻĒā§° āϗ⧁⧰⧁āĻ¤ā§āĻŦāĻĒā§‚āĻ°ā§āĻŖ āĻŦ⧈āĻļāĻŋāĻˇā§āĻŸā§āϝ


1. Pressure acts in all directions. āϚāĻžāĻĒ āϏāĻ•āϞ⧋ āĻĻāĻŋāĻļāϤ⧇ āĻ•ā§āϰāĻŋāϝāĻŧāĻž āϕ⧰⧇āĨ¤ : Liquid pressure acts sideways, upward, and downward. (āϤ⧰āϞ⧰ āϚāĻžāĻĒ āĻ•āĻžāώ⧇, āĻ“āĻĒā§°āϞ⧈ āφ⧰⧁ āϤāϞāϞ⧈ āϏāĻ•āϞ⧋ āĻĻāĻŋāĻļāϤ⧇ āĻ•āĻžāĻŽ āϕ⧰⧇āĨ¤)

2. Pressure increases with depth.āĻ—āϭ⧀⧰āϤāĻž āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧇ āϚāĻžāĻĒ āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϝāĻŧāĨ¤ : Deeper points in a liquid experience greater pressure. (āϤ⧰āϞ⧰ āĻ…āϧāĻŋāĻ• āĻ—āϭ⧀⧰ āĻ¸ā§āĻĨāĻžāύāϤ āĻ…āϧāĻŋāĻ• āϚāĻžāĻĒ āĻĨāĻžāϕ⧇āĨ¤)

3. Pressure depends on the density of the liquid.āϚāĻžāĻĒ āϤ⧰āϞ⧰ āϘāύāĻ¤ā§āĻŦā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇āĨ¤ : Denser liquids produce more pressure. (āĻ…āϧāĻŋāĻ• āϘāύāĻ¤ā§āĻŦāϝ⧁āĻ•ā§āϤ āϤ⧰āϞ⧇ āĻ…āϧāĻŋāĻ• āϚāĻžāĻĒ āĻ‰ā§ŽāĻĒāĻ¨ā§āύ āϕ⧰⧇āĨ¤)

4. Pressure does not depend on the shape of the container.āϚāĻžāĻĒ āĻĒāĻžāĻ¤ā§ā§°ā§° āφāĻ•āĻžā§°ā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āύāϕ⧰⧇āĨ¤ : Liquids at the same depth exert equal pressure regardless of container shape. (āĻāϕ⧇ āĻ—āϭ⧀⧰āϤāĻžāϤ āĻĨāĻ•āĻž āϤ⧰āϞ⧇ āĻĒāĻžāĻ¤ā§ā§°ā§° āφāĻ•āĻžā§° āϝāĻŋāϝāĻŧ⧇āχ āύāĻšāĻ“āĻ• āϏāĻŽāĻžāύ āϚāĻžāĻĒ āĻĒā§ā§°āϝāĻŧā§‹āĻ— āϕ⧰⧇āĨ¤)

Formula (āϏ⧂āĻ¤ā§ā§°) :  P = ρgh

Where / āϝ’āϤ i. P = Pressure (āϚāĻžāĻĒ)  ii. ρ = Density of liquid (āϤ⧰āϞ⧰ āϘāύāĻ¤ā§āĻŦ)  iii. g = Acceleration due to gravity (āĻŽāĻšāĻžāĻ•āĻ°ā§āώ⧀āϝāĻŧ āĻ¤ā§āĻŦā§°āĻŖ)  iv. h = Height or depth of liquid (āωāĻšā§āϚāϤāĻž āĻŦāĻž āĻ—āϭ⧀⧰āϤāĻž)

Applications / āĻŦā§āĻ¯ā§ąāĻšāĻžā§° : i. Dams are thicker at the bottom.(āĻŦāĻžāρāϧ āϤāϞāĻĢāĻžāϞ⧇ āĻ…āϧāĻŋāĻ• āĻĄāĻžāĻ  āĻšāϝāĻŧāĨ¤)  ii. Divers feel more pressure underwater. (āĻĄā§āĻŦ⧁⧰⧀āϝāĻŧāĻžāχ āĻ—āϭ⧀⧰ āĻĒāĻžāύ⧀āϤ āĻ…āϧāĻŋāĻ• āϚāĻžāĻĒ āĻ…āύ⧁āĻ­ā§ą āϕ⧰⧇āĨ¤)  iii. Water flows from holes in tanks. (āĻŸā§‡āĻ‚āϕ⧰ āĻĢ⧁āϟāĻžā§° āĻĒā§°āĻž āĻĒāĻžāύ⧀ āĻ“āϞāĻžāχ āϝāĻžāϝāĻŧāĨ¤)




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Pressure in Liquids – 2 Marks Questions with Answers : āϤ⧰āϞāϤ āϚāĻžāĻĒ – ⧍ āύāĻŽā§āĻŦā§°ā§° āĻĒā§ā§°āĻļā§āύ⧋āĻ¤ā§āϤ⧰


1. What is liquid pressure ? āϤ⧰āϞ āϚāĻžāĻĒ āĻ•āĻŋ ?


Ans: Liquid pressure is the force exerted by a liquid per unit area. āωāĻ¤ā§āϤ⧰: āϤ⧰āϞ āϚāĻžāĻĒ āĻšā§ˆāϛ⧇ āϤ⧰āϞ⧇ āĻāĻ•āĻ• āĻ•ā§āώ⧇āĻ¤ā§ā§°āĻĢāϞāϤ āĻĒā§ā§°āϝāĻŧā§‹āĻ— āϕ⧰āĻž āĻŦāϞāĨ¤













2. How does pressure change with depth in a liquid ? āϤ⧰āϞāϤ āĻ—āϭ⧀⧰āϤāĻž āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧇ āϚāĻžāĻĒ āϕ⧇āύ⧇āĻ•ā§ˆ āĻĒā§°āĻŋāĻŦā§°ā§āϤāĻŋāϤ āĻšāϝāĻŧ ?

Ans: Pressure increases with depth in a liquid. āωāĻ¤ā§āϤ⧰: āϤ⧰āϞāϤ āĻ—āϭ⧀⧰āϤāĻž āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧇ āϚāĻžāĻĒ āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϝāĻŧāĨ¤


3. Write the formula for pressure in liquids. āϤ⧰āϞāϤ āϚāĻžāĻĒā§° āϏ⧂āĻ¤ā§ā§° āϞāĻŋāĻ–āĻžāĨ¤

Ans: P = ρgh, Pressure in liquids is equal to density × gravity × height/depth.


āωāĻ¤ā§āϤ⧰: āϤ⧰āϞāϤ āϚāĻžāĻĒ = āϘāύāĻ¤ā§āĻŦ × āĻŽāĻšāĻžāĻ•āĻ°ā§āώ⧀āϝāĻŧ āĻ¤ā§āĻŦā§°āĻŖ × āĻ—āϭ⧀⧰āϤāĻžāĨ¤


4. Does liquid pressure depend on the shape of the container ? āϤ⧰āϞ āϚāĻžāĻĒ āĻĒāĻžāĻ¤ā§ā§°ā§° āφāĻ•āĻžā§°ā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇ āύ⧇āĻ•āĻŋ ?

Ans: No, liquid pressure does not depend on the shape of the container. āωāĻ¤ā§āϤ⧰: āύāĻžāχ, āϤ⧰āϞ āϚāĻžāĻĒ āĻĒāĻžāĻ¤ā§ā§°ā§° āφāĻ•āĻžā§°ā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āύāϕ⧰⧇āĨ¤


5. In which directions does liquid pressure act ? āϤ⧰āϞ āϚāĻžāĻĒ āϕ⧋āύ āϕ⧋āύ āĻĻāĻŋāĻļāϤ āĻ•ā§āϰāĻŋāϝāĻŧāĻž āϕ⧰⧇ ?

Ans: Liquid pressure acts in all directions. āωāĻ¤ā§āϤ⧰: āϤ⧰āϞ āϚāĻžāĻĒ āϏāĻ•āϞ⧋ āĻĻāĻŋāĻļāϤ⧇ āĻ•ā§āϰāĻŋāϝāĻŧāĻž āϕ⧰⧇āĨ¤


Pressure in Liquids 5 Marks Questions : āϤ⧰āϞāϤ āϚāĻžāĻĒ – ā§Ģ āύāĻŽā§āĻŦā§°ā§° āĻĒā§ā§°āĻļā§āύ⧋āĻ¤ā§āϤ⧰

 

1. Explain the properties of pressure in liquids. āϤ⧰āϞ āϚāĻžāĻĒā§° āĻŦ⧈āĻļāĻŋāĻˇā§āĻŸā§āϝāϏāĻŽā§‚āĻš āĻŦā§āϝāĻžāĻ–ā§āϝāĻž āϕ⧰āĻžāĨ¤

Ans: The important properties of liquid pressure are: āϤ⧰āϞ āϚāĻžāĻĒā§° āϗ⧁⧰⧁āĻ¤ā§āĻŦāĻĒā§‚āĻ°ā§āĻŖ āĻŦ⧈āĻļāĻŋāĻˇā§āĻŸā§āϝāϏāĻŽā§‚āĻš āĻš’āϞ:


i. It acts in all directions. (āχ āϏāĻ•āϞ⧋ āĻĻāĻŋāĻļāϤ⧇ āĻ•ā§āϰāĻŋāϝāĻŧāĻž āϕ⧰⧇āĨ¤)  ii. It increases with depth. (āĻ—āϭ⧀⧰āϤāĻž āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧇ āϚāĻžāĻĒ āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϝāĻŧāĨ¤)  iii. It depends on the density of the liquid. (āχ āϤ⧰āϞ⧰ āϘāύāĻ¤ā§āĻŦā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇āĨ¤)  iv. It does not depend on the shape of the container. (āχ āĻĒāĻžāĻ¤ā§ā§°ā§° āφāĻ•āĻžā§°ā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āύāϕ⧰⧇āĨ¤)


2. Write the formula of pressure in liquids and explain the symbols. āϤ⧰āϞ āϚāĻžāĻĒā§° āϏ⧂āĻ¤ā§ā§° āϞāĻŋāĻ–āĻž āφ⧰⧁ āϚāĻŋāĻšā§āύāϏāĻŽā§‚āĻš āĻŦā§āϝāĻžāĻ–ā§āϝāĻž āϕ⧰āĻžāĨ¤

Ans: P = ρgh
Where: = Pressure(āϚāĻžāĻĒ),  ρ = Density of liquid(āϤ⧰āϞ⧰ āϘāύāĻ¤ā§āĻŦ),  = Acceleration due to gravity(āĻŽāĻšāĻžāĻ•āĻ°ā§āώ⧀āϝāĻŧ āĻ¤ā§āĻŦā§°āĻŖ),  = Height or depth of liquid (āϤ⧰āϞ⧰ āĻ—āϭ⧀⧰āϤāĻž)


3. Why are dams thicker at the bottom ? āĻŦāĻžāρāϧ āϤāϞāĻĢāĻžāϞ⧇ āĻ…āϧāĻŋāĻ• āĻĄāĻžāĻ  āĻ•āĻŋāϝāĻŧ āϕ⧰āĻž āĻšāϝāĻŧ ?

Ans: Pressure in liquids increases with depth, so the bottom of a dam experiences greater pressure. Therefore, dams are made thicker at the bottom for strength. āωāĻ¤ā§āϤ⧰: āϤ⧰āϞāϤ āĻ—āϭ⧀⧰āϤāĻž āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧇ āϚāĻžāĻĒ āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϝāĻŧāĨ¤ āϏ⧇āϝāĻŧ⧇āĻšā§‡ āĻŦāĻžāρāϧ⧰ āϤāϞāĻĢāĻžāϞ⧇ āĻ…āϧāĻŋāĻ• āϚāĻžāĻĒ āĻĒ⧰⧇ āφ⧰⧁ āϏ⧇āχ āĻ…āĻ‚āĻļ āĻ…āϧāĻŋāĻ• āĻĄāĻžāĻ  āϕ⧰āĻž āĻšāϝāĻŧāĨ¤


4. Explain why divers feel more pressure underwater. āĻĄā§āĻŦ⧁⧰⧀āϝāĻŧāĻžāχ āĻ—āϭ⧀⧰ āĻĒāĻžāύ⧀āϤ āĻ…āϧāĻŋāĻ• āϚāĻžāĻĒ āĻ•āĻŋāϝāĻŧ āĻ…āύ⧁āĻ­ā§ą āϕ⧰⧇ ?

Ans: As depth increases underwater, liquid pressure increases. Therefore, divers feel more pressure at greater depths. āωāĻ¤ā§āϤ⧰: āĻĒāĻžāύ⧀⧰ āĻ—āϭ⧀⧰āϤāĻž āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧇ āϤ⧰āϞ āϚāĻžāĻĒ āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϝāĻŧāĨ¤ āϏ⧇āϝāĻŧ⧇āĻšā§‡ āĻĄā§āĻŦ⧁⧰⧀āϝāĻŧāĻžāχ āĻ…āϧāĻŋāĻ• āĻ—āϭ⧀⧰āϤāĻžāϤ āĻ…āϧāĻŋāĻ• āϚāĻžāĻĒ āĻ…āύ⧁āĻ­ā§ą āϕ⧰⧇āĨ¤


5. Does liquid pressure depend on container shape ? Explain. āϤ⧰āϞ āϚāĻžāĻĒ āĻĒāĻžāĻ¤ā§ā§°ā§° āφāĻ•āĻžā§°ā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇ āύ⧇āĻ•āĻŋ ? āĻŦā§āϝāĻžāĻ–ā§āϝāĻž āϕ⧰āĻžāĨ¤

Ans: No, liquid pressure depends only on depth, density, and gravity. At the same depth, pressure remains the same in all container shapes.


āωāĻ¤ā§āϤ⧰: āύāĻžāχ, āϤ⧰āϞ āϚāĻžāĻĒ āĻ•ā§‡ā§ąāϞ āĻ—āϭ⧀⧰āϤāĻž, āϘāύāĻ¤ā§āĻŦ āφ⧰⧁ āĻŽāĻšāĻžāĻ•āĻ°ā§āώ⧀āϝāĻŧ āĻ¤ā§āĻŦā§°āĻŖā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇āĨ¤ āĻāϕ⧇ āĻ—āϭ⧀⧰āϤāĻžāϤ āϏāĻ•āϞ⧋ āφāĻ•āĻžā§°ā§° āĻĒāĻžāĻ¤ā§ā§°āϤ āϚāĻžāĻĒ āϏāĻŽāĻžāύ āĻĨāĻžāϕ⧇āĨ¤