
Michael C. answered 02/14/17
Tutor
4.9
(10)
PhD with 20 years experience teaching math and applied science
First, you have to have consistency in units
km/h = 1000/3600 m/s
momentum = mass * velocity
a) Total Initial momentum = 900*70*1000/3600 + 60 * 1
= 17,560 kg.m/s
b) momentum is conserved 17,560 = 900*30*1000/3600 + 60v; v = 168 m/s
c) impulse = change of momentum = 60(168-1) =10,020 m.kg/s
d) average force = rate of change of momentum = 10,020/0.4 = 25050 J = 25.05 kJ