1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Air inside the bus?

  1. Jul 23, 2014 #1
    My doubt is reguarding the common phenomenon observed in the moving bus...While moving in a accelerating bus we all observe the wind gushing inside the bus may it be from the window of the driver or the passenger or even from the doors. My question is if all this air is entering inside the bus from where they are going out if the rear window is closed
    and even roofs are packed
  2. jcsd
  3. Jul 23, 2014 #2


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    hi there blizz

    as you have observed, the bus isn't exactly airtight. There may be a temporary increase in air pressure but I would doubt that it last long
    There's likely to be as many gaps around doors etc letting air out as there are letting air in

  4. Jul 23, 2014 #3
    Hi davenn

    If its the door u r talking about then wont u think if a person standing there would experience air entering the bus.
  5. Jul 23, 2014 #4


    User Avatar
    Science Advisor

    Sometimes air is coming in and out thought different parts of the same opening: You feel air coming in from at back of the window, but at its front part a piece of paper gets sucked out of the car.
  6. Jul 23, 2014 #5
    Actually the apparent air movement would even happen in a completely air-tight bus. As the bus begins to move, the air molecules tend to lag due to their inertia. As a result, there is a net movement of air from the front to the back of the bus. This builds up a pressure gradient, that will eventually push the air inside the bus to catch up, and the pressure evens out. The air is sloshing back.

    Here is a good demonstration :D.
  7. Jul 23, 2014 #6


    User Avatar

    Staff: Mentor

    I'm sorry, but that isn't the phenomena being described here. If the air temp is constant and absent a void such as created by the balloon, the "sloshing" is miniscule.
  8. Jul 23, 2014 #7

    Ok then, now consider a bus with a large window where a single window is shared by 2 consecutive seats( in a row) then if what u r saying is true then dont u think the passengers sitting they would experience opposite phenomenon but I personally hav experienced the opposite
  9. Jul 23, 2014 #8

    hey Boris, I think u didnt get what i asked though there might be inertia of the air particle present there but as russ said I think that effect will be too minuscule and also this is due to bus accelerating, but the phenomenon which I described can be experienced even when bus is moving with constant velocity
  10. Jul 24, 2014 #9


    User Avatar
    Science Advisor

    And I personally have experienced stuff being sucked out of the car window many times. Sometimes sucked out from the front window, and return back into the car though the back window. With a single opened window the same is possible, just within a smaller opening.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook