Hi everyone, so one day I came upon a very confusing and complicated question. I was pondering about stuff and then while watching a car it just hit me and puzzled me. So basically what I'm confused about is that do you use the same amount of gas while going at constant 100mph vs constant 10mph going up a hill. In real life for me, I find myself feeling that I have to push down more on my gas pedal for 100mph than 10mph. However, I did some calculation trying to see if it would help. Values: mass=4.37kg gravity=9.8m/s^2 coefficient between rubber (wheel) and dry concrete (road) =0.6 (source: http://hypertextbook.com/facts/2006/MatthewMichaels.shtml) Angle of hill=30 degrees Assuming air resistance and any other resistance to be the same So going up the hill at a 30 degree angle would have friction and gravity pulling u down. I calculated that Force of gravity is 35,561N and Force of friction is 9,239N. Combined total of 42,801N force that you will need to match in order for your car to keep going at a net 0 force. When I got this it still wasn't really clear. If I was going at a constant speed 100mph then it would be 0 acceleration so that would mean the car is not using any more force than going at constant 10mph. So would that be true that if I go constant 140mph to get to my destination I would burn the same amount of gas as going constant 10mph? If that's true then wouldn't I reach my destination 14 times faster and still burn the same amount of gas? But how come I always feel that I'm using more gas when i go uphill? Is it just my imagination? Thank you for everyone who can help. Appreciate it.