A stone of mass 2 kg is thrown vertically upward with an initial kinetic energy of 180 J. Taking g = 10 m/s², what is the maximum height reached by the stone?

At maximum height, all kinetic energy is converted to gravitational potential energy: KE = mgh. Therefore h = KE/(mg) = 180/(2 × 10) = 180/20 = 9 m. Option B results from using h = KE/m, forgetting to divide by g, while option D results from using h = KE/g without dividing by mass.