Classical physics is a good approximation to modern physics under certain circumstances. What are they? 0 Matter must be moving at speeds less than about 1% of the speed of light, the objects dealt with must be large enough to be seen with a microscope, and only weak gravitational elds (such as the eld generated by the Earth) can be involved. 0 Classical Physics only works when objects are large enough to hold in your hand. 0 Modern Physics applied to anything invented after the year 2000, classical physics applied to items from the 17005. O For objects at rest, we use classical physics. Objects in motion use modern physics