* Gravity's Constant Pull: Both balls experience the same gravitational acceleration (approximately 9.8 m/s²). This means they both slow down at the same rate as they go up.

* Air Resistance: Assuming we're talking about a real-world scenario, air resistance plays a role. While both balls experience air resistance, the heavier ball will be less affected by it. This is because air resistance is primarily dependent on the object's shape and surface area, and to a lesser extent, its mass.

* Time to Fall: Since the heavier ball loses less speed due to air resistance, it will reach its peak height sooner and start falling back down. This means it will hit the ground first.

Important Note: If there were no air resistance (a vacuum), both balls would reach the ground simultaneously, regardless of their mass. This is because gravity affects all objects equally, regardless of their mass.