I'm having trouble with the following problem:(adsbygoogle = window.adsbygoogle || []).push({});

"There is a car ready to go down a hill. The height of the hill is 9.0 m, and the length of the slope is 11.0 m (hypotenuse). The frictional force opposing the car is 125 N, and the car must be going 12.5 m/s when it reaches the bottom. What is the initial speed required for the car to overcome friction and reach required speed at the bottom of the hill?"

I set up the following equation: KE_i + PE_i + (frictional force)(cos 180)(11.0 m) = KE_f

I don't know if I have the right setup because whenever I try to solve it, I run into trouble because there is no mass provided and I get an answer to be around 50 (it should be a little less than 3 m/s).

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Non-conservative forces

**Physics Forums | Science Articles, Homework Help, Discussion**