Final answer:
The rock that starts from rest and falls for 1.23 seconds will be moving at approximately 12.054 meters per second, calculated using the formula V = g * t, where g is 9.8 m/s².
Step-by-step explanation:
The student's question is about determining how fast a rock is moving after falling from a cliff for 1.23 seconds, assuming the rock starts from rest and there is no air resistance. To find the velocity of the rock after 1.23 sec, we use the equation of motion for an object under the influence of gravity:
V = g * t
Where V is the velocity, g is the acceleration due to gravity (9.8 m/s²), and t is the time in seconds. Substituting in the given values:
V = 9.8 m/s² * 1.23 s = 12.054 m/s
Therefore, the rock will be moving at approximately 12.054 meters per second after falling for 1.23 seconds from rest.