Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    • Thread Starter
    Offline

    16
    ReputationRep:
    Calculate the relative uncertainty, in percent, of:
    The density of a cuboid block of iron whose lengths are known to 2% and whose mass is known to 0.1%. (Equation: density=massvolume)

    Can someone help me with this question please, I've been stuck on it for so long, I don't get it.
    Offline

    4
    ReputationRep:
    I might be wrong, but I think this is just a simple sum, the answer being you have to add up the percentage uncertainties. When you are multiplying/diving two values with known %uncertainty, you just add both of the %uncertainties together. Volume of a cuboid is l x l x l so the %uncertainties of length would add up, equallling 2%+2%+2% = 6%
    Density = mass x volume so the %uncertainty is 0.1%+6% = 6.1%

    Here are some threads to help you out :
    http://www.thestudentroom.co.uk/show....php?t=2661762
    http://www.thestudentroom.co.uk/show....php?t=2622706
    Offline

    11
    ReputationRep:
    (Original post by azefayuu)
    I might be wrong, but I think this is just a simple sum, the answer being you have to add up the percentage uncertainties. When you are multiplying/diving two values with known %uncertainty, you just add both of the %uncertainties together. Volume of a cuboid is l x l x l so the %uncertainties of length would add up, equallling 2%+2%+2% = 6%
    Density = mass x volume so the %uncertainty is 0.1%+6% = 6.1%

    Here are some threads to help you out :
    http://www.thestudentroom.co.uk/show....php?t=2661762
    http://www.thestudentroom.co.uk/show....php?t=2622706
    Yes, you simply add the percentage uncertainties.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: February 1, 2016
Poll
Do you agree with the proposed ban on plastic straws and cotton buds?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.