Problem 7: The springs are undeformed when xi(t) = x2 = x3 = x4 = 0 at t = 0. Given X₁ > X3.

x₁(t)

m₁

K

voo

B1

[

K

voo

X3

#

m4

m3

m₂

B3

B₂

B₁

+

K

voo

K

000

a) Draw the free body diagram of the four masses.

b) How many modeling equation(s) are there? Note: No need to find/write modeling equation(s).