Engine power is sometimes expressed in terms of "horsepower." One horsepower was defined by James Watt, who observed that a horse could walk 3.3 km/hr while exerting a nearly constant force of 816 N. (a) What is the conversion for horsepower to kilowatts? (b) If you wanted to run a car just using solar panels, how big an area of solar panels would you need to produce the power of 200 horsepower, used in a car?