Spring in moving elevator!

  1. 1. The problem statement, all variables and given/known data

    Three masses m1 = 3.1 kg, m2 = 9.3 kg and m3 = 6.2 kg hang from three identical springs in a motionless elevator. the elevator is moving downward with a velocity of v = -2.3 m/s but accelerating upward with an acceleration of a = 4.8 m/s2. (Note: an upward acceleration when the elevator is moving down means the elevator is slowing down.) What is the force the bottom spring exerts on the bottom mass?

    2. Relevant equations


    3. The attempt at a solution

    Some of my confusion lies with k. Since k is a constant is it the same value as if the elevator was motionless or does k change when the elevator moves?
  2. jcsd
  3. The spring constant k is constant in the elastic region of the spring. Assume this for your solution.
  4. Still not sure how to solve this I guess
  5. Draw your Free-Body Diagram first.
  6. SammyS

    SammyS 9,269
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    How is it this possible "... a motionless elevator. the elevator is moving " ?

    Follow flyingpig's advice !!!
  7. PeterO

    PeterO 2,319
    Homework Helper

    I think he means the masses are motionless wrt the lift and not bouncing around - but yes free body diagram.
Know someone interested in this topic? Share this thead via email, Google+, Twitter, or Facebook

Have something to add?