A 2 kg rock is dropped from rest at height of 30 metres above the ground how much heat energy is generated when it hits ground

How is coal extracted from mountaintop removal mines? a. dynamite is used to create underground tunnels where miners go to extract the coal. b. dynamite is used to break apart rocks and then draglines are used to remove the broken rock and reach the coal. c. coal in mountaintops is extracted by digging strips in the landscape to reach the coal. d. placer deposits in mountain river bottoms are removed by

Which accurately compares concave and convex lenses?

What is the measurement of how fast an object moves relative to a reference point?