1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Couple of uncertainty questions

  1. Aug 14, 2009 #1
    1. The area of a circle has a fractional uncertainty of 0.08 (i.e. 8%), what is the fractional uncertainty of it's radius?

    So i suppose you have to use A = pi(r^2) and rearrange, bit confused though...

    2. Square wave has a height of 2.4cm +/- 0.2cm. This signal is applied across a resistor of R = 10.0 +/- 0.2 ohm. What is the fractional uncertainty in the heating power dissipated by the resistor?

    Figured this is the right formula... P = (V^2)/R

    again a bit unsure how to do it.

  2. jcsd
  3. Aug 14, 2009 #2


    User Avatar

    Staff: Mentor

    As you should know, we don't do your work for you. How should you use uncertainties and those formulas to calculate the final uncertainties? If the equation is linear, the transfer of the uncertainty depends on what? If the equation is non-linear, the uncertainty depends on what? Read your textbook...
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook