A stone is thrown up from the surface of earth when it reaches a maximum height it's kinetic energy is equal to

Kinetic energy at maximum height is zero.

Explanation:

At maximum height, the velocity is zero. Thus, the kinetic energy is also zero. This can further be seen as illustrated below:

Let the mass of the object be = m

Velocity (v) at maximum height = 0 m/s

Kinetic energy (KE) at maximum height =?

KE = ½mv²

KE = ½ × m × 0²

KE = ½ × m × 0

KE = 0

From the illustration above, we can see that the kinetic energy at maximum height is zero.