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Interesting problem ... basic engineering solution

gkenyon
So, today's engineering problem goes like this.


Someone in our family is dying their hair. The chemical (probably a Chromate-based hair dye) must be mixed with 180 ml of water at between 40 and 50 °C - if the temperature is too low, mixing is very difficult, too high and the compound breaks down, and perhaps you might not get the hair colour you need.


Simples ... except we have no thermometer.


How was this quick and easy to resolve?


Parents
  • 0
    I don't think the tap water in the summer months would have been 10 degrees C, I think you're correct at 15 degrees C, certainly up to a few weeks ago ... of course the temperature when you first turn on the tap may well be warmer unless someone has just used a quantity of water in the premises.


    When I did the calculation, I actually did separate sheet for cold winter (5 degrees), late autumn / early spring at 10 degrees, 15 degrees for the majority of warmer months, and 20 for the periods when it's consistently baking for a few days.



    I never bothered checking too closely on how critical the temperature was - following the manufacturer's instructions for the temperature range required.


    The idea of this post, was to illustrate some engineering principles, the sorts of things we do on a day-to-day basis at work to make things happen in novel ways due to constraints, and the basic difference between science and engineering being we're used to working with tolerances and unknowns, and fashioning these to bring the result in the acceptable range.
Reply
  • 0
    I don't think the tap water in the summer months would have been 10 degrees C, I think you're correct at 15 degrees C, certainly up to a few weeks ago ... of course the temperature when you first turn on the tap may well be warmer unless someone has just used a quantity of water in the premises.


    When I did the calculation, I actually did separate sheet for cold winter (5 degrees), late autumn / early spring at 10 degrees, 15 degrees for the majority of warmer months, and 20 for the periods when it's consistently baking for a few days.



    I never bothered checking too closely on how critical the temperature was - following the manufacturer's instructions for the temperature range required.


    The idea of this post, was to illustrate some engineering principles, the sorts of things we do on a day-to-day basis at work to make things happen in novel ways due to constraints, and the basic difference between science and engineering being we're used to working with tolerances and unknowns, and fashioning these to bring the result in the acceptable range.
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