Driving home from school one day, you spot a ball rolling out into the street. You brake for 1.20 s, slowing your 950-kg car from 16.0 m/s to 9.50 m/s. (a) What is the average force exerted on your car during breaking? (b) How far did you travel while breaking?
When I solved to get acceleration I got $$\frac{(9.5-16)}{1.2} = -5.42 m/s^2$$
Then to find (a) I did $$\sum{F} = ma$$ $$\sum{F} = (950)(-5.42)$$ $$\sum{F} = -5149 newtons$$
I guess my question is: Can the newtons be negative or are they an absolute value to where there always positive?