three masses 3.4 kg, 10.2 kg and 6.8 kg, hang from 3 identical springs in an elevator moving downward with v = -2.3 m/s and acc upward @ a = 4.9 m/s^2. What is the force the bottom spring exerts on the bottom mass? I got that part 100 N. other given spring constant k=238 and springs initial is .14m. Now they are asking the difference the upper spring is extended. I've tried to use F = ma I used all the weight 20.4 * 4.9 then I used F = -kx , F/-k = x and got -.42m they say it is wrong I don't know what I did wrong can you help me please?

Question

three masses  3.4 kg, 10.2 kg and 6.8 kg, hang from  3 identical springs in an elevator moving downward with v = -2.3 m/s and acc upward @ a = 4.9 m/s^2. What is the force the bottom spring exerts on the bottom mass? I got that part 100 N. other given spring constant k=238 and springs initial is .14m.  Now they are asking the difference the upper spring is extended. I've tried to use F = ma I used all the weight 20.4 * 4.9 then I used F = -kx , F/-k = x and got -.42m they say it is wrong I don't know what I did wrong can you help me please?

anonymous · Answer

when you are calculating mg is g= 9.81 m/s^2 or -9.81 m/s2 when dealing with kinetic friction problems?

anonymous · Answer

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