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!

Force Elevator Problem!

  1. Oct 13, 2010 #1
    1. The problem statement, all variables and given/known data
    Your mass is 65 kg. You stand on a bathroom scale in an elevator on Earth.

    (a) What force would the scale exert when the elevator moves up at a constant speed?

    (b) What force would the scale exert when it slows at 2.1 m/s2 while moving upward?

    (c) What force would the scale exert when it speeds up at 2.1 m/s2 wile moving downward?

    (d) What force would the scale exert when it moves downward at a constant speed?

    (e) What force would the scale exert when it slows to a stop at a constant magnitude of acceleration?

    2. Relevant equations
    f=ma
    fg=mg
    fnet=mAnet
    Ff=μῦFn


    3. The attempt at a solution
    I honestly have no idea what to do with all these Y forces going everywhere..Can someone walk me through the process of solving this problem?

    THANK YOU IN ADVANCE FOR ANY HELP!!
     
  2. jcsd
  3. Oct 13, 2010 #2

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Draw free body diagrams. There are 2 forces acting on the person, the person's weight, acting down, and the normal (scale) force acting up. Use Newton's laws F_net = ma when accelerating. At constant speeed or at rest, F_net =0 (no acceleration, per newton 1). Please show an attempt .
     
  4. Oct 13, 2010 #3
    I found (a), (c), and (d), but I can't find (b). Here is my attempt at solving it:

    mAnet = -Fn + Fg
    mAnet - Fg = -Fn
    65(-2.1) - 65(9.81) = -Fn
    774.15 = Fn

    Help?
     
  5. Oct 13, 2010 #4
    I also don't understand how to find (e)..
     
  6. Oct 13, 2010 #5
    Okay after working on this, I've solved it. Thanks anyways!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Force Elevator Problem!
  1. Elevator force problem (Replies: 1)

Loading...