This is the answer given: a) KE=(1/2)(m)(v-u) 2 Conversion: u = (41km/hr)(1hr/36

Question

This is the answer given:

a) KE=(1/2)(m)(v-u)2
    Conversion: u = (41km/hr)(1hr/3600s)(1000m/km) =11.39m/s
                      v =(51km/hr)(1hr/3600s)(1000m/km) = 14.17m/s
    KE =(1/2)(2100kg)(14.172-11.392) = The Answer fora)

b)Momentum= m((v2+u2)), v=14.17i u=11.39j
    =2100((14.172+11.392)) = Answer forb)

c)tan = (11.39/14.17) = Degrees South of East



What I don't understand is where they got momentum from. I thoughtmomentum was p=mv, but here they altered it so much, i'm not surewhat they're doing with it.

Explanation / Answer

velocity V = 14.17 i + 11.39 j So, magnitude of V = [ 14.17 ^ 2 + 11.39 ^ 2]                               = 18.18 m / s So, momentum P = m V                            = 2100 * 18.18                            = 38178.5 kg m / s

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