Answer:
Vf = 28 m/s
Explanation:
In order to find the final velocity of the rock, we will use the 3rd equation of motion. The third equation of motion for vertical direction is written as follows:
2gh = Vf² - Vi²
where,
g = acceleration due to gravity = 9.8 m/s²
h = height dropped = 40 m
Vf = final velocity of the rock = ?
Vi = Initial Velocity of the rock = 0 m/s (since, rock was initially at rest)
Therefore,
(2)(9.8 m/s²)(40 m) = Vf² - (0 m/s)²
Vf = √(784 m²/s²)
Vf = 28 m/s
