What is an inertial reference frame?
In inertial frame of reference is one that is not accelerating. A frame of reference in a gravitational field you could be considered to be accelerating. That is why, when you are considering all the forces acting, you have to include the weight of the object. W = mg where m is the mass and g is the acceleration due to gravity. A rotating frame of reference is accelerating – surface of the earth for example. You need to include Coriolis Force to explain the observed motion. Usually this is so small that it can be ignored. In considering atmospheric motions you can’t ignore it. If you did you would not be able to explain why the wind blows in the cyclonic direction (in the same direction as the rotation of the earth) around low pressure. In an accelerating lift, you need to include that acceleration. A car traveling along a straight road with constant gradient (or level) is an inertial frame of reference (when you include weight). Including weight, all the laws of motion will be observe
