We need to convert Km/hr to m/s so must multiply by 1000 m/km and divide by 3600 secs / hr

so speed = 100/3.6 = 27.8 m/s

Its initial momentum was MV = 755 * 27.8 = 2.1 * 10 ^4 Ns

During braking an amount of impulse = FT = 2.5 * 5.2 * 10^3 = 1.3 * 10 ^ 4 Ns has been lost.

So the final momentum is initial - lost
= 2.1 * 10 ^ 4 - 1.3 * 10 ^ 4 = 7990 Ns

Now once more momentum = MV
so 7990 = 755 * V
V = 7990 / 755 = 10.6 m/s ( about 37 Km/hr)

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