I think that the HSC online verison seems to be a good example.
Remember that an inertial frame of reference is one with a constant velocity while a non-inertial fram of reference is one experiencing an acceleration. A good way to see the difference is to hang a bob (weight of some sort) on a string.
If you hold the string in an inertial frame of reference then the bob will be hanging directly down since the net force acting on the system is zero. Should the frame of reference accelerate (hence becoming non-inertial) then you will notice that the bob sways outward in a direction dependent upon the net force acting on the system.
With a knowledge of the mass of the bob and its angle to the horizontal you can work out the forces acting on the bob using vector addition. (note* A Force = an acceleration = non-inertial)
