Recent content by djdoug99

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    Large heatsinks in refrigerator?

    Water has a heat capacity 4 times that of aluminum, but If I can position the heat sinks in the front of the refrigerator (closer to the incoming warm air), will that be just as effective as water jugs in the back?
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    Large heatsinks in refrigerator?

    I'm trying to keep my refrigerator cold when I have the door open and have read about putting water jugs in the back to help stabilize the temperature when the door is left ajar. Instead of water, would large aluminum heatsinks (with fins) work just as well? Thanks Don
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    Does Fastener Member Stiffness Need to be Multiplied by 2 in Calculations?

    I am going through Shigley's Mechanical Design book and have a quick question on fasteners. Sometimes when calculating the spring rate for a member, you have to multiply the rate by 2, why is this? For instance in this problem http://imgur.com/2ug9AaR When the spring rate is calculated for...
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    Question about fluid flow and pressure in pipes

    Thanks for your response Travis. What I'm trying to do is measure the pressure in a 1/8" tube. The place that I want to measure the pressure won't be open to the atmosphere. I'm concerned that If I break the the 1/8" tubing and put inline a bigger pvc fitting (3/4") with an attached gauge then I...
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    Question about fluid flow and pressure in pipes

    Does a pipe have to be completely filled with a fluid to measure its pressure? For instance if I have a small diameter pipe that diverges to a bigger pipe. The small pipe will be completely filled with water, but will the bigger pipe be? If the bigger pipe is only half full of flowing water...
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    High altitude balloon acceleration

    But if it was constant than its acceleration would be constant so it would be going close to 300 m/s at a certain altitude. This of course is without the drag force accounted for.
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    High altitude balloon acceleration

    Im using these equations: http://www.grc.nasa.gov/WWW/K-12/airplane/atmosmet.html I'm still getting a constant buoyant force for some reason. If someone could take a look at my excel sheet that would be great. The ideal gas law is being used to calculate the baloons volume at different...
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    High altitude balloon acceleration

    bump.. or anyone have another idea how I can approximate the acceleration at various altitudes?
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    High altitude balloon acceleration

    Yes it is. I guess I wasn't paying attention when I was typing that in. Its been fixed in the original post. I'm aware that the volume of the balloon will increase as it climbs which is my problem since the amount of air displaced will also increase. I just don't know how to model the change of...
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    High altitude balloon acceleration

    I'm trying to calculate the acceleration of a high altitude balloon at different altitudes. In excel I've got the temperature, air pressure, and air density for a given altitude (thanks to NASA). Right now I am calculating the net force on the balloon with: Fnet= Fb-Fm Fb = Buoyant force =...
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    Ground question and pen voltage detectors.

    So then isn't everything technically grounded. It just depends on the amount of resistance that determines the amount of current delivered. Or does being 'grounded' suggest that the subject is directly connected to ground through a conductor?
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    Ground question and pen voltage detectors.

    Hi, I am new here and have a couple questions. First, If someone is standing in their house on a carpeted floor with rubber soled shoes on and they only touch the hot wire, will they get a shock? Also, can anyone explain how those pen voltage detectors work where you only have to touch one...
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    Electric current and voltage question

    http://www.allaboutcircuits.com
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    Exponential Population Growth: 1970-1980

    I'll give you the equation you need to use. P(t) = P0ekt P(0) = P0 Use the information given in the problem to find your constant (k). Once you have that it is very easy. Cool, first post!
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