78% nitrogen, 21% oxygen
ionosphere
temperature falls to -93*c
temperature continue to rise up to 1500*c
temperature drops from 17 to -52*c
protective ozone layer
uv radiation causes temperature to rise

You have a resistor and a capacitor of unknown values. first, you charge the capacitor and discharge it through the resistor. by monitoring the capacitor voltage on an oscilloscope, you see that the voltage decays to half its initial value in 3.00 ms . you then use the resistor and capacitor to make a low-pass filter. what is the crossover frequency fc?

Atrain is traveling at 30.0 m/s relative to the ground in still air. the frequency of the note emitted by the train whistle is 262 hz. the speed of sound in air should be taken as 344 m/s. what frequency (f approach) is heard by a passenger on a train moving at a speed of 18.0 m/s relative to the ground in a direction opposite to the first train and approaching it? what frequency (f recede) is heard by a passenger on a train moving at a speed of 18.0 m/s relative to the ground in a direction opposite to the first train and receding from it?

Scientists and engineers design new technologies to solve problems. often, a new technological design will contain a flaw. which of the following is true about such a flaw? a. it should be studied so that the design can be fixed or a new design can be proposed. b. it means that the problem being investigated cannot be solved. c. it means that the people who proposed the design should not be scientists or engineers. d. it makes the technological design useless.