How is Earth's surface most likely to change in a place that experiences extensive animal activity? Sand dunes will be formed due to deposition of sediments.
Soil will loosen due to vast network of underground tunnels.
Cracks will appear in rocks due to freezing and thawing of water.
Rocks will break due to repeated abrasion and mechanical stress.

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

When you jump from an elevated position you usually bend your knees upon reaching the ground. by doing this, you make the time of the impact about 10 times as great as for a stiff-legged landing. in this way the average force your body experiences is a) less than 1/10 as great. b) more than 1/10 as great. c) about 1/10 as great.d) about 10 times as great.

Lightning is an example of what phenomenon? a release of a large amount of energy an absorption of a large amount of energy a natural electric circuit a natural electric current