CBSE Class 11-science Answered

The below figure shows the frame of reference in physics.        

            The choice of a frame of reference is determined by our own convenience. For describing the motion of bodies on the earth, we choose a frame of reference rigidly connected to the earth, which is regarding as a fixed body. However, in reality the earth is in circular motion. In investigation of the earth’s motion, we attach the coordinate system to the sun.

            In studying the sun’s motion, we choose a reference frame connected to the stars. Sometimes, we choose the floor or walls of a room as the reference frame which may be at rest with respect to the earth or which may be in motion if it is on a train or in a spacecraft.

            The choice of a frame of reference is arbitrary. Therefore, a passenger in a moving train may claim to be at rest and declare that the electric poles and trees moving backward while a person standing on the ground claims that the train is moving forward. Both are evenly correct. On the basis of our daily experience, we intuitively choose a frame of reference attached to the earth and describe the motion of various bodies. Thus, in the reference system attached to the earth, it is the train that moves forward.