Question

A runner with a mass of 80kg accelerates from 0 to 9 m/s in 3 s find the net force

Answer 1

So, first you find your acceleration which is 3m/s^2, using the acceleration formula.
Now set up your equation, F=ma, so put in the stuff, F=80kg·3m/s^2. Then solve your equation by multiplying, and you get F=240N, since newtons are your measurement.
Hope this helps