V = (pi) * r^2 * h
h = 7
V = 252(pi)
252(pi) = r^2 * 7
252(pi) / 7 = r^2
36(pi) = r^2
sqrt 36(pi) = r
6 = r <==== radius is 6 cm
Let the slower train's velocity be x-21
Let the faster train's velocity be x
We know that the approach speed is the sum of both speeds, so x+x -21= 2x-21.
The approach rate is given by Distance/time = 471/3 = 157mpH
x+x-21=157
2x=157+21
2x=178
x=89mph
The slower train is travelling 89-21 = 68mph
The faster train is travelling 89mph.
