## 4 thoughts on “3.48”

1. cangy23 says:

So you can just assume that all of the masses are moving in the same direction? Is the purple plate moving to the right? If this is the case, would some of the spring and dampers be in tension and some of them be in compression?

Thanks,

Nick

1. tutorpaul says:

We can make any motion assumption we find fastidious. I made the assumption that all the masses and the plate move to the right, notice directly to the right of the drawing of the system I indicated the specific motion assumption that $x_1 > x_2 > x_3$ as well as $x_2 > x_4 > x_5$. This means that all of the springs are in compression. Of course, you are free to make any assumption you like, but easier assumptions make the problem a little easier to analyze. Whichever assumption you make you should get the same result so long as you understand the implications of your assumption. If you haven't seen it you should check out my video on motion assumptions.

2. Redacted says:

Shouldn't f(t) be positive on the second line of the summed forces for the second mass?