Answer:
A. 36,000 W
Explanation:
[tex]m[/tex] = mass of the car = 900 kg
[tex]v_{o}[/tex] = Initial speed of the car = 20 m/s
[tex]v_{f}[/tex] = Final speed of the car = 0 m/s
[tex]W[/tex] = Work done by the brakes on the car
Magnitude of work done on the car by the brakes is same as the change in kinetic energy of the car.hence
[tex]W = (0.5) m (v_{o}^{2} - v_{f}^{2})\\W = (0.5) (900) ((20)^{2} - (0)^{2})\\W = 180000 J[/tex]
[tex]t[/tex] = time taken by the car to come to stop = 5 s
[tex]P[/tex] = Average power produced by the car
Average power produced by the car is given as
[tex]P = \frac{W}{t} =\frac{180000}{5} \\P = 36000 W[/tex]
