Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: A drag force question

  1. Oct 4, 2005 #1
    The first part of a pretty involved, 8 part question on modelling drag force states: "A 0.142 kg ball has a terminal speed of 42.5 m/s. If a ball experiences a drag force of R=CV^2, what is the value of the constant, C?

    I know this is a ridiculusly easy problem, but our text doesn't cover the formula for drag force at all, and I'm not sure what the R variable is. I mean, I know that v is velocity, so you'd think by elimination, R must be somehow represent mass, but the answer that produces isn't accepted by the homework system. So, who wants to tell me what R is, and possibly make fun of my ignorance a little too? Any takers?
  2. jcsd
  3. Oct 4, 2005 #2


    User Avatar
    Science Advisor
    Homework Helper

    Use F = ma = drag force, with the left side determined by gravity's force, and the right side given by the drag force.

    Don't worry about it being ridiculously easy. If that's your worst problem this semester you done good.

  4. Oct 4, 2005 #3

    James R

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    The question tells you "a drag force of R=..."

    That is, R is a force - a drag force.
  5. Oct 4, 2005 #4
    Okay, I see. Thanks for the assistance.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook