3. A 10 kg rock rests on top of a cliff 10 meters above the earth's surface.If the rock falls and all of its energy is conserved what is its kinetic energy the second just before it hits the ground? (Show work) 4. 0J. B . 98J C. 480J D. 980 J

## Step 1The problem involves the principle of conservation of energy, which states that the total energy in an isolated system remains constant. In this case, the rock's potential energy is converted into kinetic energy as it falls.## Step 2The potential energy (PE) of the rock when it is at rest on the cliff can be calculated using the formula:### where is the mass of the rock, is the acceleration due to gravity, and is the height of the cliff.## Step 3Substituting the given values into the formula, we get:### ## Step 4As the rock falls, all of its potential energy is converted into kinetic energy. Therefore, the kinetic energy of the rock just before it hits the ground is also 980 J.