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

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.

3752.5*9.80= 36774.5 N

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?

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.

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

To calculate the retarding force acting on the car, you can use Newton's second law of motion, which states that force equals mass multiplied by acceleration. In this case, the acceleration can be calculated using the following kinematic equation:

v^2 = u^2 + 2as

where:
v = final velocity (0 m/s, as the car comes to rest)
u = initial velocity (28.0 m/s)
a = acceleration (unknown in this case)
s = distance (79.0 m)

Rearranging the equation to solve for acceleration:

a = (v^2 - u^2) / (2s)

Plugging in the values:

a = (0^2 - 28.0^2) / (2 * 79.0)
a = (-784) / 158
a ≈ -4.96 m/s^2

Since the car is decelerating (slowing down), the acceleration is negative.

Now, you can calculate the retarding force by multiplying the mass of the car (1330 kg) by the acceleration:

force = mass * acceleration
force = 1330 kg * (-4.96 m/s^2)
force ≈ -6600 N

So, the retarding force acting on the car is approximately -6600 N (negative because it acts in the opposite direction to the car's motion).