1. The problem statement, all variables and given/known data A 1200 kg car slows down from 90km/h to 70 km/h in about 5.0s on the level when it is in neutral. Approximately what power ( in watt's and hp ) is needed to keep the car travelling at a constant 80km/h? 2. Relevant equations P = W / t 3. The attempt at a solution I really have no idea ............ and how much does 1hp = in watts and in joules ? 550 ft lbs/s = in joules and watts?