Show that an object with a mass of 8.00kg can have the same kinetic energy as an object with a mass of 32.0kg
KE = 1/2 * m*v^2
So if KE is to be the same and m is different, v must be different also. I would plug 8.00 kg in for mass and make up a KE, solve for v. Then using that KE and 32 kg, solve for the new v.