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: Help with an air resistance problem.

  1. Sep 20, 2010 #1
    Part A)
    A raindrop of mass 1.06 × 10−5 kg falls in air
    and reaches a terminal speed of 4 m/s.
    The acceleration of gravity is 9.8 m/s2 .
    What is the value of the constant k that
    determines the resistive force F = k v ?
    Answer in units of kg/s

    Part B)
    If there were no air resistance, how long would
    it take the raindrop to reach the same speed?
    Answer in units of s.

    I'm sorry there's no work, but I just have no idea where to start. We haven't even learned about air resistance in my class yet, and I was assigned this for homework.
  2. jcsd
  3. Sep 20, 2010 #2


    User Avatar
    Homework Helper

    Start by drawing a free-body diagram, what are the forces acting?

    If the resultant force is downward, using the forces you listed, form an expression for the resultant force.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook