Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Vaccum Problem

  1. Apr 7, 2008 #1
    1. The problem statement, all variables and given/known data
    The Bruce Nuclear Development is a CANDU style reactor. This means that it has a "vaccum building" to "suck" (the contents of a malfunction reactor to a safer place. Refer to the engineering "specs" for the needed information to calculate the net force of the atmposhere acting on the building.

    Dimensions of building- 51.m tall .914m thick and 52.1m diameter
    Pressure- 90kpa outside of building and 10.3 kpa inside of the build

    2. Relevant equations
    mother formula-P= F/A
    F= PxA

    3. The attempt at a solution
    so I'm guessing you add the to pressures you have so it would be 100.3 kpa

    surface are of building-51mx52.1mx.914m=2 428.5 m squared

    2428.5m x 100.3kpa=
    2428.5 x 100 000=242 858 94 0N
  2. jcsd
  3. Apr 7, 2008 #2
    Well, if you were finding the pressure difference, you'd need to subtract, not add. However it's not as simple as that since the internal area and external area of the building are not the same due to the thickness of the walls.

    It sounds like this building is a cylinder, but you've taken the measurements to be the length/width/depth and calculated what the volume would be in this case.

    Have a think about how to calculate the area of the inside and outside of the building. Then use the respective pressures to calculate the forces on the inside and outside. After that, it's just a subraction.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook