# Spring in moving elevator!

1. Sep 26, 2011

### mrshappy0

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

f=-kx

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. Sep 26, 2011

### edgepflow

The spring constant k is constant in the elastic region of the spring. Assume this for your solution.

3. Sep 27, 2011

### mrshappy0

Still not sure how to solve this I guess

4. Sep 27, 2011

### flyingpig

5. Sep 27, 2011

### SammyS

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