1- A freight train consists of two 8.0010^5-kg engines and 45 cars with average masses of 5.5010^5kg. What force must each engine exert backward on the track to accelerate the train at a rate of 5.0010^2 m/s2 if the force of friction is 7.5010^5N, assuming the engines exert identical forces? This is not a large frictional force for such a massive system. Rolling friction for trains is small, and consequently, trains are very energy-efficient transportation systems. 2- By what factor does the drag force on a car increase as it goes from 65 to 110 km/h