Understanding Pressure

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

Learner's Guide


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?




What is Force?




Effects of Force:




What is Thrust?





What is the unit of Thrust?

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






Pressure: a measure of force's effectiveness:



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

True or False?

Show|Hide Answer



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


  • 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


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


Login to comment