Physics

The time it takes for the rock to hit the ground depends on several factors such as air resistance, the rock's mass and shape, and the surface it is falling onto. Additionally, gravitational acceleration on Earth is 9.8 meters per second squared. That means that the rock would have an initial velocity of 0 and its speed will increase by 9.8 m/s every second until it hits the ground. So, if we assume that air resistance is negligible, the time it will take for the rock to fall 64 feet is approximately 6.5 seconds. At the time of impact, its velocity will be 64 feet divided by 6.5 seconds, or roughly 9.8 m/s (21.7 mph).