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!

Finding Terminal Velocity given Mass and magnitude

  1. Mar 24, 2013 #1
    I'm in physics 1 in college and reviewing for an up comming exam, ran into this problem and cant seem to figure out how to solve it.

    A 70 kg skydiver experiences a drag force as a function of velocity (in m/s), opposite the direction of motion, whose magnitude is given

    Fd(v)=0.19v^2

    What is the skydiver's terminal velocity?

    Any help would be appreciated!
     
  2. jcsd
  3. Mar 24, 2013 #2

    TSny

    User Avatar
    Homework Helper
    Gold Member

    Hi, Matt h. Welcome to PF!

    The rules here require you to show some attempt at a solution before receiving help. So, how do you think you could get started on this problem? What physics principles or laws are relevant?
     
  4. Mar 24, 2013 #3
    Oh, ok

    Using F=ma i found out that the force due to gravity is
    70kg*9.81m/s^2=686.7N

    Would i then just plug this force into the magnitude equation above to find the velocity?

    After plugging it in i got 60.1 m/s

    Does that sound about right?
     
  5. Mar 24, 2013 #4

    TSny

    User Avatar
    Homework Helper
    Gold Member

    Yes, that looks very good. Do you see why you should set the magnitudes of the two forces equal to each other?
     
  6. Mar 24, 2013 #5
    I'm not sure that i do, do you mind explaining it?
     
  7. Mar 24, 2013 #6

    TSny

    User Avatar
    Homework Helper
    Gold Member

    Newton's 2nd law: Fnet = ma

    For an object moving at terminal velocity, what is the value of the acceleration a?
     
  8. Mar 24, 2013 #7
    Acceleration would be 0, right?

    or no acceleration?
     
  9. Mar 24, 2013 #8

    TSny

    User Avatar
    Homework Helper
    Gold Member

    Yes. So,...:smile:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted