# physics

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A car of mass 1330 kg is traveling at 28.0 m/s. The driver applies the brakes to bring the car to rest over a distance of 79.0 m. Calculate the retarding force acting on the car.

(79.0/28.0)*1330
3752.5

I asked before but I wasn't sure if I did it right

• physics -

No, you didn't work it right. Check the units in your work, your answer comes out as kg-second. Is that a force? You can do better than this.

• physics -

3752.5*9.80= 36774.5 N

• physics -

Jon, I stated once you were just plugging numbers guessing, and you were really put off by that. Guess what you are doing?

Physics is not getting the answer. It is analysis.

a car has a kinetic energy. Some force applied over a distance must equal that KEnergy.

Has it occured to you that you might set KE equal to forcefriction*distance, and solve for forcefriction?

• physics -

No I havent thought of that. I know physics isnt just getting the answer my problem is figuring out WHAT to analyze on some of these problems.

• physics -

this is just one of the things I just don't get. this time Im plugging in numbers I think are going to help me solve the problem 1330kg(9.8)=13034N I changed it to newtons I just thought that's what I was suppose to do