In this activity, we will observe the rectilinear motion of an object. We all know the rectilinear motion of an object is the motion of an object in a straight line or a straight path. For this activity, we need a glass marble, we need poster colour and a white sheet. We take a glass marble, put it in a colour and it should be thickly coated with the colour. Roll it on a white sheet of paper. What do we observe? We observe the movement of the marble in a straight line. This shows that the marble moves in a straight line or a rectilinear motion. So we define rectilinear motion as the motion of an object in a straight line.