A diesel locomotive weighing 100 tons pulls a carriage weighing 50 tons along a horizontal section of the trajectory

A diesel locomotive weighing 100 tons pulls a carriage weighing 50 tons along a horizontal section of the trajectory. Figure 28 shows a graph of the dependence of the projection of the train speed on the X-axis from time to time. Determine the traction force developed by the locomotive and the elongation of the hitch, if its stiffness is 400kN / m. Solve the problem considering two cases: a) there is no friction in the system; b) * coefficient of friction is 0.01.

a) Solution:
5 = 12a
a = 0.42 m / s ^ 2
Ft = ma = 63,000 N
x = 63,000/400,000 = 63/400 = 0.16 m
Answer: 63 kN; 0.16 m

b) Solution:
F = ma-Ftr. = 63000-15000 = 48kH
x = 48/400 = 0.12 m
Answer: 48 kN; 0.12