At what height above the ground must a body of mass 8kg be situated in order to have potential energy equal to kinetic energy possessed by another body of mass 12kg moving with a velocity of 10ms-1 (with the procedures).
KE = 1/2 mv^2
PE = mgh
so you want
8*9.81 * h = 1/2 * 12 * 10^2
now just crank it out