1. The problem statement, all variables and given/known data Ok this question came up on a car forum and i tried to answer it, but I think my answer is way to simple and I solved the problem incorrectly 1. A 2072lb Opel GT goes up 20 degree incline how much horsepower will the car need to get up the hill at the same speed as the same car on the ground. The car on the ground has 102 HP 2. I didn't solve this one: Both cars now start from rest and travel a quarter mile. Assuming the car on the ground completes the distance in 18 seconds how much HP will be needed for the car on the incline to finish in the same amount of time. (accel is constant) Dont worry about friction or air resistance all things are equal. 2. Relevant equations mgcosΘ and mgsinθ 3. The attempt at a solution The force against a 9210.46 Newton (2072lb) Opel GT on an incline of 20° would be equal to mass*gravity(sin20°) which rounds to about 3153 newtons (708.8 lbs) So without any air resistance, friction, wheels falling off, fuel leaks, drivers, passengers, or dead bodies in rear console, your Opel would "weigh" 2780.8lbs. Let's say you have the top spec stock high comp GT with 102HP. Your HP to weight ratio would be .03668009 hehe (very roughly 1 hp per 27.8 lbs) On the ground your HP to weight ratio is 0.04922779! (Very roughly 1 HP per 20.7 lbs) Xhp/2780.8=.04922779 Hp up hill would have to be about 137hp to equal the car on the level surface!