Find height of a building using barometer

September 30th, 2006 12:54 pm by SiLent_Man

Sir Ernest Rutherford, President of the Royal Academy, and recipient of the Nobel Prize in Physics, related the following story.

Some time ago I received a call from a colleague. He was about to give a student a zero for his answer to a physics question, while the student claimed a perfect score. The instructor and the student agreed to an impartial arbiter, and I was selected.

I read the examination question: “Show how it is possible to determine the height of a tall building with the aid of a barometer.” The student had answered: “Take the barometer to the top of the building, attach a long rope to it, lower it to the street, and then bring it up, measuring the length of the rope. The length of the rope is the height of the building.”

The student really had a strong case for full credit since he had really answered the question completely and correctly! On the other hand, if full credit were given, it could well contribute to a high grade in his physics course and certify competence in physics, but the answer did not confirm this.

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5 Responses to “Find height of a building using barometer”

  1. 1
    Sjogren Says:

    Brilliant answerssssssss……

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  2. 2
    myself Says:

    hehehe……….smart answer

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  3. 3
    undone Says:

    Y a barometer? it didnt really measure the altitude. I dont get it.

    *scratching thick head*

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  4. 4
    Sandman Says:

    well, atmospheric pressure varies with different altitude, so I guess thats why the person was given a barometer, although I don’t think people use barometers to measure altitudes (help me out here physics studs).

    The moral of this story is to think outside the box I guess… :-)

    Kinda reminds me of my Statistics (Quantitative Methods) Prof who always used to say “I will give you marks only for your methodology and not on whether you arrive at the correct answer or not”. Damn I always used to flunk that course because of that. :-(

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  5. 5
    xxx Says:

    height = (RT/Mg)ln(Pground/Pheight)

    See derivation of the hypsometric equation here

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