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: Elevator Tension With Upward Acceleration

  1. Oct 15, 2012 #1
    1. The problem statement, all variables and given/known data

    An elevator weighing 10 000N is supported by a steel cable. Determine the tension in the cable when the elevator is accelerated upward at 3.0 m/s2

    A) 7.0kN
    B) 10.0 kN
    C)11.6 kN
    D) 13.1 kN
    E) 40.0 kN

    2. Relevant equations

    F=ma W=mg (g=9.8m/s^2)

    3. The attempt at a solution
    10 000=m(9.8)
  2. jcsd
  3. Oct 15, 2012 #2
    The net force (i.e. the total of all the forces) is what causes acceleration in the equation F=ma. So draw a diagram and label the forces acting on it. (Gravity and Tension) so now use the F=ma equation and plug everything in and off you go.
  4. Oct 15, 2012 #3
    So it would be
    10 000=m(9.8)


    3060+10 000 = F
    F= 13.1 kN?
  5. Oct 15, 2012 #4
    Remember that the force of gravity is opposite the force of tension. One's up and one's down.
  6. Oct 15, 2012 #5
    So the 3060 would be subtracted from the elevators weight because it's accelerating upwards (against gravity) making it 7000?
  7. Oct 15, 2012 #6
    Oh my goodness, I'm sorry, you were right in the first place, I read it wrong. Good work! Sorry to confuse.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook