Q2 Z2,(Q2) Z2(Q2) - Institute for Water Resources - U.S. Army

To dotermine the distance traveled during an acceleration from
v = 0 to v = plq, the definite integral of Equation (3.25) from
t 0 to t = T a is obtained, i.e., where. D a is acceleration distance,
r a
v dt = .L D = In
a k
0
2
R i - R 9 R 1 Ta
KT I 2k 2
a
e KTa - R
2
I
2
(3.27)
No general solution, such as Equation (3.24), exists in the case
of the equation of.motion applicable to rail trains, Equation (3.21) .. -
distance for vehicles possessing such an equation of motion. These
will be presented in Chapter V in the discussion of the rail process
function.
Deceleration State. Deceleration is a good deal more complicated
than is acceleration because (1) it may consist of coasting and brak-
ing stages and (2) additional resistance forces, e.g., engine drag,
may occur. That is, if the motive force ceases, the vehicle will
coast to a stop. One can hasten the process by adding drag forces
such as braking or reversing engines. One mist make assumptions about
how much drag forces are increased; and, apparently, engineering prac-
tice is to assume coasting and braking at constant rates. 12 Then the
time, T c , required to coast from one constant velocity, V, to another,
V c , at a constant rate c is
T c = (V - V)/c. 13 (3.28)
There are, however, various ways to estimate the acceleration time and
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