Which of the choices below gives a true example of how a natural resource can be renewed? a. when all of the coal is gone from a mine, new coal can be grown in its place. b. when forests have been cut down, new native trees can be planted. c. when an area's natural gas has been used up, oxygen can replace the gas. d. when the sun is hidden behind clouds, lamps can be used to power solar cells.

Which of the following is not am example of a polymer? protein nylon kevlar concreta

Atwo-stage air compressor operates at steady state, compression 10m^3/min of air from 100 kpa and 300k to 1200 kpa. an intercooler between the two stages cools the air to 300k at a constant pressure of 350 kpa. the compression processes are isentropic. a) calculate the power required to run the compressor, in kw b) compare the result to the power required for isentropic compression from the same inlet state to the same final pressure.

You are given two vectors a⃗ =−3.00ι^ 5.00j^ and b⃗ =5.00ι^ 2.00j^. let the counterclockwise angles be positive.