Calculate the efficiency of a hairdryer that has a total power input of 2000W and a useful power output of 1200W.

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

Do you agree with scientist’s prediction about the warming of alaska and other polar regions?

Argon, neon, and xenon are examples of