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: Newton sliding/falling block

  1. Oct 1, 2006 #1
    The problem is this: There are two blocks of unknown masses M1 and M2. M1 is sitting on a frictionless table and M2 is attached to m1 by a massless string and is hanging over the edge over a pulley. If m1 is four times more massive than m2, how far will m1 travel in 0.633 seconds?
    So far I've gotten
    a= (m2/m1+m2)g .
    I replaced m1 with 4*m2, and then simplified the equation to give me
    a=(1/5) 9.8
    a= 1.96 m/s^2.

    Once I had the acceleration, I then used the fact that a=v/t to give me the velocity, and then I multiplied the velocity by the time to give me distance.
    1.96=v/.633 sec
    I then multiplied that by the time in order to give me the distance.
    v*t= 0.785 m

    I entered this into the homework on the internet and it says I'm wrong, I don't know what else to do? Can anyone help me on where I messed up?
  2. jcsd
  3. Oct 1, 2006 #2
    it's not a=v/t, but a=dv/dt.

    you did solve for v correctly and a correctly though and you almost have the right answer. the error is in the last part of your work.

    what does (velocity)(time)=distance mean?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook