1. The problem statement, all variables and given/known data A car weighing 1940lb has lost its brakes and is unable to come to a stop. A police cruiser of 3900lb gets ahead of it so that the two cars are now bumper to bumper. The combined cars are now traveling at 60mph down a 15 degree grade slope. If the police cruiser can normally brake from 60mph to rest in 250ft if it is on level ground: A) How long will it take for the police cruiser to bring both cars to a stop? B) How far will they have traveled during this time? Ignore friction. 2. Relevant equations F= ma V^2 - Vo^2 = 2a∆x 3. The attempt at a solution The first thing i did was convert everything into SI units for simplicity. Speed of Cars 26.8 m/s Mass of car 881kg Mass of police cruiser 1770kg Weight of car 8643N Weight of police cruiser 17360N Weight of Combined Cars 26000N I then determined the breaking force Fb of the police cruiser's brakes by determining first the acceleration of caused by the brakes, and then finding the force using F=ma [V^2 - Vo^2] / [2∆x] = a ab= [0 - (26.8m/s)^2]/[2(76.3m)] = -4.71m/s^2 Fb=mab F=(1770kg)(-4.71m/s^2) = -8337N So the force applied by the brakes of the police is -8337N The next thing i did was draw a free body diagram of the cars going down a 15 degree slope. So if the cars are currently moving at a speed of 26.8m/s down the slope, this means they are not accelerating? right? Im confused about what to do next . ∑Fx = Wx - Fbx ??