1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Forces with blocks problem

  1. Oct 1, 2009 #1
    1. The problem statement, all variables and given/known data
    Blocks of 1.0, 2.0, and 3.0 kg blocks are lined up on a table (1kg block being on the left, 2kg in the middle, 3kg being on the right). A rightward poiting 12 N force is applied to the leftmost block. What force does the leftmost block exert on the middle one?

    2. Relevant equations

    a= Force applied / (m1 + m2 +m3)
    a= 12N/6k= 2m/s^2

    3. The attempt at a solution
    Ok so this is what I did:

    12N + F(1on2)=(mass of 2nd block)(acceleration)
    F(1on2)=8N, I got this wrong. Did i miss something, or should this force actually be negative.
  2. jcsd
  3. Oct 1, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    You got he acceleration right and that is good.

    The 1 kg block exerts a force on the middle block that is to the right. The 3 kg block exerts a force on the the 2 kg block that is to the left. You don't have that one. Added together these forces are the net force on the 2 kg block.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook