Understanding the Physics

* Free Fall: This means the only force acting on the rock is gravity.

* Acceleration due to Gravity: We'll use the standard acceleration due to gravity on Earth, which is approximately 9.8 m/s². This means the rock's velocity increases by 9.8 meters per second every second it falls.

Using the Equations of Motion

We can use the following kinematic equation to find the final velocity (v):

* v = u + at

where:

* v = final velocity

* u = initial velocity (which is 0 m/s since the rock is dropped)

* a = acceleration due to gravity (9.8 m/s²)

* t = time (3.5 seconds)

Calculation

1. Plug in the values:

v = 0 + (9.8 m/s²)(3.5 s)

2. Calculate:

v = 34.3 m/s

Answer

The velocity of the rock as it reaches the ground is approximately 34.3 m/s.