Two spherical balls of masses m₁ = 32.0 kg and m₂ = 45 kg are linked by a thread which is passed over a cylindrical pulley of radius r = 0.422 m and mass 2.5 kg. The system is initially held still in such a state that m₁ is on the floor while m₂ is at a height of 4.2 m above the floor. Using the principle of conservation of energy, calculate the speed of m₂ just when it hits the floor after the system is released. Assume that there is no friction.