Now, three masses (m1 = 3.1 kg, m2 = 9.3 kg and m3 = 6.2) hang from three identical springs in a motionless elevator. The springs all have the same spring constant given above.

Question

Now the elevator is moving downward with a velocity of v = -2.9 m/s but accelerating upward at an acceleration of a = 3.6 m/s2. (Note: an upward acceleration when the elevator is moving down means the elevator is slowing down.)
What is the magnitude of the net force on the middle mass?
I got 33.48 by using F=ma and that was wrong, so was the negative answer. I might be using the wrong formula, how would I solve this and how would that look like?

Answer 1

What is the distance the lower spring is extended from its unstretched length?
this is another one I had trouble with, how would I go about doing this one?

Answer 2

first, calcuate the force on each spring due to motion: F=m(g+a)
Next, calculte how far each spring is extended to those individual forces.
x=forceonspring/k

Answer 3

is this for the distance or the magnitude?

Answer 4

Look the "net" force on a rigid body is its mass times its acceleration, like period.
for spring extension I need to know your geometry, series or parallel. Which is the top mass if in series?