Power output question

Practice Question Solving
1

A 800kg compact car delivers 20% of its output to its wheels. If the car has a mileage of 30 miles/gallon and travels at a speed of 60 miles/hour, how much power is delivered to the wheels? 1 gallon of petrol contains 9 * 10⁸ J

Hi everyone,
The answer to this question is 100 kW, how can we solve?
Thanks!!

2

First, calculate the rate of petrol consumption:

Therefore, the total power is:
2 gallons/hour x 9x10^8 J/gallon
= 18x10^8 J/hour
= 18x10^8 J/3600 s
= 5x10^5 J/s = 5x10^5 W

20% of the total power output is delivered to the wheels so 20% of 5x10^5 W is
20/100 * 5x10^5 W = 10^5 W = 100 kW