you throw a 4kg rock directly down at 6m s from the top of a 18m cliff calculat 1

a)initial Kinetic energy 

b)Initial Potential Energy

c) Velocity when rock is 13m above ground

d) Velocity rock will hit the ground 

e)distance the rock is driven into the mud if the mud exerts a steady upwards force of 4000N 

f)speed the rock hits ground if initially thrown upwards at 6m/s