After driving at a constant speed of 72 km / h for 10 minutes, a car consumes 1.2 kg of gasoline, half of which is converted into traction and recharges the battery The electric energy stored in the battery increases by 7.2 × 10 ^ 6J. How much resistance does the car suffer? (the calorific value of gasoline q = 4.6 × 10 ^ 7J / kg, and Q discharge = QM)

After driving at a constant speed of 72 km / h for 10 minutes, a car consumes 1.2 kg of gasoline, half of which is converted into traction and recharges the battery The electric energy stored in the battery increases by 7.2 × 10 ^ 6J. How much resistance does the car suffer? (the calorific value of gasoline q = 4.6 × 10 ^ 7J / kg, and Q discharge = QM)

Distance traveled by car s = VT = 72km / H x 10 / 60H = 12km = 12000m
Heat released from gasoline q = MQ = 1.2kg x 4.6 x 10 ^ 7J / kg = 5.52 x 10 ^ 7J
And 0.5q discharge = w useful (work done by traction) + W electricity
So w useful = O.5 x 5.52 x 10 ^ 7j-7.2 x 10 ^ 6J = 2.04 x 10 ^ 7J
It can be concluded that f s is useful
F traction force = w / S = 2.04 x 10 ^ 7J / 12000m = 1700n