Question

Suzy likes to drive with a silly sun ball on her car antenna. The frontal area of the ball is 0.0040 m². As gas prices rise, her husband is concerned that she is wasting fuel because of the additional drag on the ball. He runs a quick test in the wind tunnel at his university and measures the drag coefficient to be 0.30 at nearly all air speeds.

Determine the overall car efficiency (with 2 decimal places) if 300 litres of fuel are wasted every year. Use the following additional information: She drives about 20000 km per year at an average speed of 35 m/s. (? fuel = 0.92 kg/L, the heating value of the fuel is 60000 kJ/kg, ? air = 1.2 kg/ m³, and µ = 1.8 × 10⁻⁵ kg/ms).

Answer 1