Explain why, if we look at objects through the hot air over a fire, the objects appear to be moving (or shaking) slightly.

When we look at some object through our eyes then image formed on the retina is

STATEMENT -1 : For an observer looking out through the window of a fast moving train , the nearby objects appear to move in the opposite direction to the train , while the distant objects appear to be stationary . STATEMENT - 2 : If the observer and the object are moving at velocities vec v_(1) and vec v_(2) respecttively with refrence to a laboratory frame , the velocity of the object with respect to a laboratory frame , the velocity of the object with respect to the observer is vecv_(2) - vecv(1) .