Compare between trapezoidal and quadrilateral speed-time curves.
Answers
Let α and ß be the acceleration and retardation respectively in m/s2, Vm be the crest speed in m/s and T be the total time of run in seconds.
Simplified Speed-Time Curves.JPG
Fig. 8.2
Acceleration period, t1 = Vm/ α
Retardation period, t3 = Vm
Retardation period, t3 = Vm/
Free running period, t2 = T – (t1 + t3)
= T – (12
Where is the coasting retardation in m/s2
Total distance travelled,
S =
Where ßc is the coasting retardation in m/s2
Total distance travelled,
S = 1/2 V1t1 + v1 + v2/2 X t2 + 1/2 V2t3
Or S = T/2 ( V1 + V2) - 1/2 V1 V2 ( 1/α + 1/ß
From the above expression the value of unknown quantity can be determined by substituting the values of known quantities.
Simplified Speed-Time Curves1.JPG