Understanding Pressure

What is Force, Thrust, and Pressure? Atmospheric Pressure and Pressure applied by liquid.

Learner's Guide

Motivation:

In this session, we will find the answer to following questions:

    • What is force?
    • What is thrust?
    • What is pressure?
    • How does air exert pressure?
    • How do liquids exert pressure?

 

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What is Force?

1/7

 

 

Effects of Force:

 

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What is Thrust?

 

1/8

 

 

What is the unit of Thrust?

  1. Same as unit of force
  2. Newton
  3. Meter
  4. Kilogram
Show|Hide Answer

Answer:

Thrust is a type of force.

So unit of thrust is same as force.

Unit of Force = Unit of thrust = Newton

 

Correct answer: 1 & 2

 

 

 

Effectiveness of Force:

 

1/9

 

 

 

Pressure: a measure of force's effectiveness:

 

 

If you apply more force, it will always be more effective.

True or False?

Show|Hide Answer

Answer:

False.

Effectiveness of force depends on surface area and amount of force.

 

 

 

Pressure Exerted by Atmosphere and Liquids:

 

Why do we use mercury in barometer and thermometer?

Show|Hide Answer

Answer:

  • It is liquid at room temperature.
  • It's characteristics do not change with change in pressure and temperature over a big range.
    • For example: it behaves same at 10 ATM and at 1 ATM pressure.
    • It behaves same at 100 degrees a 1 degree temperature.

 

 

 

Tip: Think before answering.

  •  

    According to above image, Pressure on surface is:

    1. F1/surface area
    2. F1
    3. F2
    4. F2/Surface area
    Difficulty Level: Moderate

    F1/surface area

     

    Pressure = Force acting perpendicular to surface / surface area.

  • Effectiveness of force = _______________

    1. Thrust
    2. Perpendicular Force
    3. Effective Force
    4. Pressure
    Difficulty Level: Easy
  • Pressure is measured by _______________

    1. Manometer
    2. Barometer
    3. Thermometer
    4. 1 & 2
    Difficulty Level: Moderate

    1 & 2

    Barometer = Atmospheric Pressure

    Manometer = Liquid Pressure

  • Which of the following metal is used in barometer?

    1. Lead
    2. Mercury
    3. Aluminium
    4. Glass
    Difficulty Level: Easy
  • Atmospheric pressure is caused by ____________

    1. Weight of air
    2. Motion of air particles
    3. Both weight and motion
    4. None
    Difficulty Level: Moderate

    Both weight and motion.

    Gas particles are always in motion. Thus majority of pressure is contributed as they strike the surface.

  • Liquid exert pressure because of _____________

    1. Movement of particles
    2. Weight
    3. None
    Difficulty Level: Easy
  • If we increase the surface area, pressure will decrease.

    True or False.

    Difficulty Level: Moderate

    True.

    If we increase surface area, same force will get divided and thus effectiveness of it will decrease.

Discussion

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