The given equation for the height of a lava fountain is:
y = (1/2)gt^2
where y is the height in meters, g is the acceleration due to gravity (approximately 9.8 m/s^2), and t is the time in seconds.
To find the height of a lava rock that falls for 3 seconds, we can substitute t = 3 into the equation:
y = (1/2)(9.8 m/s^2)(3 s)^2 = (1/2)(9.8 m/s^2)(9 s^2) = 44.1 meters
Therefore, the height of a lava rock that falls for 3 seconds is approximately 44.1 meters.