Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Newton's Law

  1. Jul 11, 2006 #1
    Assume there is negligible friction between the blocks and the table. Compute the tension in the cord and the acceleration of m2 if m1 = 300g, m2 = 200g, and F=0.4N

    I figured out that T=m2*a2, F-2T=m1a1.
    According to the answer, 2a1=a2. But I don't undestand why.

    Attached Files:

  2. jcsd
  3. Jul 11, 2006 #2

    Doc Al

    User Avatar

    Staff: Mentor

    acceleration constraint

    Your force equations are correct, but incomplete. You need to incorporate the constraint imposed by the fact that the masses are connected via a pulley and ropes--that's what will give you the additional equation a2 = 2 a1. To understand where that relationship comes from, answer this question: If m1 moves one meter to the right, how far does m2 move? (If you have trouble visualizing the motion, use a piece of string or a paper strip.)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook