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: Two blocks attached by a string(dynamic)

  1. Feb 21, 2013 #1
    1. The problem statement, all variables and given/known data
    Two blocks (m1=4.0kg, m2=7.5kg) are attached by a light cord pulled along a horizontal surface by a force of 53N as shown in the diagram. If the coefficient of friction between the blocks and the surface is 0.30, what is the tension in the rope between the two blocks.

    M2 -------- M1 ------->Force applied

    2. Relevant equations
    Fnet= Ma

    3. The attempt at a solution

    I used the Fnet=ma, on m1 i got Fapplied - T - Ff = ma
    But i dont know how to find the acceleration. And i know theres two different frictions because of two different mass. So i dont know how to join them together and find Tension.

    ps: I just joined this forum, What should i do if i have a a lot of questions or simply want someone to check over my assignment for me before I hand them in? (got like 20-30questions). I dont want to violate the rule so im just wondering if theres a specific section to post or something.
  2. jcsd
  3. Feb 21, 2013 #2
    What about M2?
    Apply Newton2 to M2 and then you'll have 2 equations to work with.

    If you have other questions you want to post, then create a new thread for each one.
  4. Feb 21, 2013 #3
    Hmm, ok so now i got this.



    plug a into m1's equation

    T=34.565N = 35N

    If someone can check if i did the calculation right, it would be greatly appreciated.

    Thank you.
  5. Feb 21, 2013 #4
    Yes, this is correct :)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook