Two stones are thrown up simultaneously from the edge of a cliff 200 m high with initial speeds of 15 m s-1and 30 m s-1. Verify that the graph shown in Fig. 3.27 correctly represents the time variation of the relative position of the second stone with respect to the first. Neglect air resistance and assume that the stones do not rebound after hitting the ground. Take g = 10 m s-2. Give the equations for the linear and curved parts of the plot.
What is rest?
When an object does not change its position with time, with respect to it's surroundings. In such a case the object is said to be at rest.
What is the most essential thing to study the motion of a body?
The most essential thing to study the motion is reference frame. Rest and motion are relative terms. It means that an object in one situation can be in rest but in another situation, the same object will be in motion.