Hi @Leonardo
I cannot provide the physical explanation of how the student author derived the model. Mathematically, the 1st-order transfer function’s output requires approximately 
time units to rise from 0 and converge to A, where A is the response amplitude (steady state).
time units to rise from 0 and converge to A, where A is the response amplitude (steady state).
v = 30; % wheel speed in RPM
Tr = -10; % brake torque requirement
A = v*Tr*(-0.01)*1; % Amplitude (steady state value of brake pressure)
s = tf('s');
tau = 0.1;
G = A/(tau*s + 1)
step(G, 1), grid on
xline(0.5, '--')
Despite the physical signal port of the Disk Brake measuring brake pressure in bars, the Simscape unit manager can automatically verify units within a physical network and perform the necessary conversions, provided the user correctly specifies the incoming signal unit (N/m^2, i.e., pascal, Pa).
