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: Find the Normal Force of a box in an elevator cab

  1. Oct 28, 2009 #1
    1. The problem statement, all variables and given/known data

    Elevator cabs A and B are connected by a short cable and can be pulled upward or lowered by the cable above cab A. Cab A has mass 1700 kg; cab B has mass 1300 kg. A 12.0 kg box of catnip lies on the floor of cab A. The tension in the cable connecting the cabs is 1.91×10^4 N. What is the magnitude of the normal force on the box from the floor?"

    2. Relevant equations


    3. The attempt at a solution

    T = mB(a+g)

    N=m(a+g) = m (T/mB)= (12.0)(1.91×10^4/1300) = 176 N (rounded value)
  2. jcsd
  3. Oct 28, 2009 #2


    User Avatar
    Homework Helper

    Why did you drop the "g" in this step? Other than that, it looks good to me.
  4. Oct 28, 2009 #3
    I found that a+g=T/mB
    So, I replaced a+g by T/mB
  5. Oct 28, 2009 #4


    User Avatar
    Homework Helper

    You are correct! I bungled the move from Mb to the catnip.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook