1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    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!

Having trouble understanding the relationship between these expressions

  1. Apr 16, 2012 #1
    38v5P.png

    I understand everything up until:

    √MgL/m = L/t

    Why is that equal to L/t?

    I also don't understand this either:

    U8IiJ.png

    This is the problem itself however I don't feel it's that important since I am trying to figure out how they are arriving at their conclusions.

    An astronaut on a small planet wishes to measure the local value of the free-fall acceleration by timing pulses traveling down a wire that has an object of large mass suspended from it. Assume a wire has a mass of 4.10 g and a length of 1.60 m and that a 3.00 kg object is suspended from it. A pulse requires 43.6 ms to traverse the length of the wire. Calculate g of planet from these data. (You may ignore the mass of the wire when calculating the tension in it.)
     
  2. jcsd
  3. Apr 16, 2012 #2
    They are not saying that the last equality follows from something about [itex]\sqrt{MgL/m}[/itex], but rather that the wave speed [itex]v[/itex] is equal to both [itex]\sqrt{T/u}[/itex] AND [itex]L / t[/itex] (since speed is just distance divided by time).

    The second section is just an algebraic rearrangement of the second equation in the first section.
     
  4. Apr 16, 2012 #3
    Yeah okay that went through my head for a split second but I couldn't find that in my book so I didn't know where they pulled it from. Thank you!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook