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!

Crate Friction on Horizontal Floor

  1. Oct 17, 2004 #1
    I have a problem with an answer that I don't know how to arrive at.

    There is a 35 kg crate on a horizontal floor that a person is pushing with a 110 N force. The coefficient of static friction is 0.37. What is the maximum value f of s, max for which the crate will not move?

    I thought that the answer is f of s, max = (coefficient of static frction)(35 kg)(9.8 m / s^2) = 127 N. However, the book lists an answer of 130 N. Am I going about his problem correctly?
     
  2. jcsd
  3. Oct 17, 2004 #2
    You're absolutely correct! [tex]f_{s, max} = \mu_s N = \mu_s mg[/tex] Because there are only 2 significant digits in the values for [tex]m, \mu_s[/tex] etc., the answer should be expressed with only 2 significant digits. You got an answer of 127 N which contains 3 significant digits. The book simply rounded up to 130 N to express the answer in 2 significant digits. Wasn't that simple? You were doing everything correctly!
     
  4. Oct 17, 2004 #3
    Thank you for the reassurance! I don't think I would have gotten any further in the assignment stressing over that one little answer! :redface:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?