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 Newton's law

  1. Oct 25, 2004 #1
    Hi, I have been given this problem to do as extra credit:

    An inventive child named Pat wants to reach an apple in a tree without climbing the tree. Sitting in a chair connected to a rope that passes over a frictionless pulley, Pat pulls on the loose end of the rope with such a force that the spring scale reads 250 N. Pat’s true weight is 320 N, and the chair weights 160 N.

    Show that the acceleration of the system of Pat and the chair is upward and find its magnitude.

    Find the force Pat exerts on the chair.


    I made 3 free body diagrams, but am stuck.

    Thanks in advance for any help.
  2. jcsd
  3. Oct 25, 2004 #2
    Can you show us your free body diagram?
  4. Oct 25, 2004 #3
    I dont have access to a scanner so Ill try to draw them as best as I can:

    Pat - A ^
    480 N

    Spring scale - A \/
    250 N

    Pat on Chair -A \/

    Are these right? What would the proper equations be?

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook