Two stones are thrown vertically upwards simultaneously with their initial velocities $u _{1}$ and $u _{2}$ respectively. Prove that the heights reached by them would be in the ratio of $u_{1}^{2}: u_{2}^{2}$ (Assume upward acceleration is $-\,g$ and downward acceleration to be $+g$.

Area under speed$-$time graph is equal to the

$(a)$ Define uniform circular motion.

$(b)$ Ram goes for a morning walk in a circular park daily. He completes one revolution of the park in $4$ minutes. Find his speed if the diameter of the park is $420\, m$.

$(c)$ Draw velocity$-$time graph for uniform motion along a straight line. How can you find distance covered by a body from this graph ?

What do you understand by the displacement$-$time graph ? Draw a displacement-time graph for a girl going to school with uniform velocity. How can we calculate the uniform velocity from it ?

Name the force which is responsible for change in position or state of an object.