A ball at rest falls from a platform above the ground. The ball falls freely and hits the ground 3 s later. What is the height of the platform?
(use -9.8 m/s2 today for the acceleration due to gravity)

Answer (d) the universe had cooled enough for atoms to combine, protons and neutrons were too far apart to form nuclei;

At maximum height, kinetic energy is converted in potential energy  formula: at max height, ke = ½ * 0.27kg * (16m/s) ² = 34.56 j  so the remaining pe = (41.70 – 34.56)= 7.14 j = 0.27 kg * 9.8m/s² * h  = (9.8/7.14 * 0.27)so max height h = 5.08 or 5 m