How many kilocalories are generated when the brakes are used to bring a 1200-kg car to rest from a speed of 95 km/h? 1 kcal = 4186 j?

Answer: 1st, identify the givens and the unknown - this will give you parameter of what concept and formula are you going to use. Given: m = 1200kg v initial = 95km/hr v final = 0 2nd, focus on the units - in most cases units speak for the concept the unit of the unknown is kcal, thus its the unit of energy or work so, W = ? 3rd, provide the appropriate formula - give formula or equation that the given and the unknown are present since W = delta K. E = delta P. E W = 0.5m (vf^2 - vi^2) - - - > best formula 4th, Substitute the given to the formula since 1 Joule = 1Nm 1N = 1kgms^-2 1cal = 4.19 J we express first 95 km/hr to m/s 95km/hr x 1000m/1km x 1hr/3600sec = 26.39 m/sec W = 0.5 (1200kg) [ (0^2 - (26.39m/sec) ^2] W=600 kg (0 - 696.43m^2/s^2) W=600kg (-696.43m^2/s^2) W=417859.3Nm or 417859.3 J W = 417859.3 J x 1 cal / 4.19 J W = 99,727.7 cal or 99.728 kcal