Final answer:
The speed of the rock when it hits the ground is approximately 7.33 m/s.
Step-by-step explanation:
When a rock is dropped from a height, it falls freely under the influence of gravity. The speed at which it is going when it hits the ground can be calculated using the equation v = sqrt(2gh), where v is the final velocity, g is the acceleration due to gravity (approximately 9.8 m/s^2), and h is the height from which the rock is dropped.
In this case, the height from which the rock is dropped is 2.7m. Plugging this value into the equation, we get:
v = sqrt(2 * 9.8 * 2.7) = sqrt(53.64) = 7.33 m/s
Therefore, the rock is going approximately 7.33 m/s when it hits the ground.