Answer:
The magnitude of the stone velocity before it hits the ground is 30 m/s.
Explanation:
Given;
initial vertical velocity,
final vertical velocity, = 30 m/s
Apply the following kinematic equation to determine the height of the cliff;
Determine time of the journey;
h = vₓ + ¹/₂gt²
vₓ = 0 (initial horizontal velocity when the stone was thrown vertically downward)
h = ¹/₂gt²
t = √ (2h / g)
t = √ (2(40.82) / 9.8)
t = 2.89 s
When the rock is projected horizontally, the horizontal distance, x = 40.82 m
Initial horizontal velocity,
The final vertical component of the velocity is given by;
The magnitude of the stone velocity before it hits the ground is given by;
Therefore, the magnitude of the stone velocity before it hits the ground is 30 m/s.