question_answer

A car of mass 1 ton moving with a velocity of 90 kmph is brought to rest in 20 S. What is the brake power?

Answer:

Mass of the car = 1 ton = 1000 kg; velocity of \[car=90\,\,kmph=90\times \frac{5}{18}=25m/s\] Time = 20 s ; Power = ? We know that, \[P=\frac{Work\,\,done}{time}=\frac{K.E.}{t}=\frac{{}^{1}/{}_{2}m{{v}^{2}}}{t}\] \[\Rightarrow P=\frac{{}^{1}/{}_{2}\times 1000\times 25\times 25}{20}=15625=15.625\,\,K.W.\]