A train accelerates at a rate of 2.5 km/hr/sec. During the acceleration period, its velocity changes by 55 km/hr. Choose the exact time of the train's acceleration.

A. 1,200 s

B. 22 hr

C. 22 s

D. 0.045 s

Using the formula:

v = u + at

a = accelaration = 2.5 km/hour^2

v = final velocity = 55 km / hour

u = initial velocity (in this case u=0)

t = time

hence,

v = 0 + at

v = at

55 km / hour = 2.5 km/hour^2 * t

t = 55 km / hour / 2.5 km/hour^2

t = 22 hours