A toy remote-controlled car with mass 3.70kg is moving at the top of a 7.0m high hill. The car rolls down the hill and experiences an average force of kinetic friction of 10.5N, so the child operating it guns the engine and provides 4.1W of power for 2.50s. The car then rolls to the top of another 2.5m tall hill, where it has a velocity of 8.38 m/s upon reaching the top. If the car covered a total distance of 5.5m , what was the initial velocity of the car at the top of the first hill?