# Spring in moving elevator!

by mrshappy0
Tags: elevator, moving, spring
 P: 98 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?
P: 688
 Quote by mrshappy0 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?
The spring constant k is constant in the elastic region of the spring. Assume this for your solution.
 P: 98 Still not sure how to solve this I guess
 P: 2,568 Spring in moving elevator! Draw your Free-Body Diagram first.
 Emeritus Sci Advisor HW Helper PF Gold P: 7,819 How is it this possible "... a motionless elevator. the elevator is moving " ? Follow flyingpig's advice !!!
HW Helper
P: 2,318
 Quote by SammyS How is it this possible "... a motionless elevator. the elevator is moving " ? Follow flyingpig's advice !!!
I think he means the masses are motionless wrt the lift and not bouncing around - but yes free body diagram.

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