Suppose, a ball of mass M is thrown upwards from a point A and it...

Let the reference level for potential energy be at point A. Thus, the potential energy at A is zero.

When the ball is thrown upwards from point A with velocity $v$, its kinetic energy is $\dfrac{1}{2}Mv^2$.

Total mechanical energy at A is $E_A = \dfrac{1}{2}Mv^2 + 0 = \dfrac{1}{2}Mv^2$.

At the highest point B, the velocity of the ball becomes zero, so its kinetic energy at B is zero.

Let the height of point B from A be $h$. The potential energy at B is $Mgh$.

Total mechanical energy at B is $E_B = 0 + Mgh = Mgh$.

According to the law of conservation of mechanical energy, the total energy at A equals the total energy at B.

$E_A = E_B \Rightarrow \dfrac{1}{2}Mv^2 = Mgh$

Therefore, the kinetic energy at A is equal to the potential energy at B.

Answer: Kinetic Energy at A = Potential Energy at B