To find the time it took for the stone to travel 123 meters at a speed of 30 meters per second, you can use the formula:
Time = Distance / Speed
In this case, the distance is 123 meters, and the speed is 30 meters per second. Plugging these values into the formula, we get:
Time = 123 meters / 30 meters per second
Time = 4.1 seconds
So, the stone traveled for 4.1 seconds to cover a distance of 123 meters at a speed of 30 meters per second.