If the velocity is constant then the acceleration of the object is zero.

Thus when we apply the equation

It remains

or equivalent
210J
PE is mgh in this context.
Here as we know that there is no loss of energy
so we can say that maximum kinetic energy will become gravitational potential energy at its maximum height
So here we have

here we have
v = 20 m/s
m = 8000 kg
now from above equation we have



so maximum height is 20.4 m
1950 g This is the answer due to the kilograms of lead being distributed