Answers

2016-03-12T13:23:07+05:30
Given,
mass, m = 3000 kg
initial velocity, u = 72km/h = 20m/s
final velocity, v = 0m/s (Since it stops)
Force, F = 24000 N

Work Done = change in kinetic velocity =  \frac{1}{2}m(v^{2}-u^{2})
=> Work Done = [text]\frac{1}{2}(3000(0^{2}-20^{2}))[/text]
=> Work Done = 600,000 J

Therefore, Work Done = 6 *  10^{5} J
We know, Work done = Fs (s =displacement)
=> 6 *  10^{5}  = 24000 * s
=> s = 25m
7 5 7