Suppose a galaxy formed stars for a few million years and then stopped (and no other galaxy merged or collided with it). what would be the most massive stars on the main sequence after 500 million years? after 10 billion years? how would the color of the galaxy change over this time span? (refer to evolution from the main sequence to red giants.)

Explain how plate tectonics have changed earth’s surface over time. include the role of plate tectonics in the creation of landforms.

1point) a skydiver weighing 130 lb (including equipment) falls vertically downward from an altitude of 14,000 ft and opens the parachute after 20 s of free fall. assume that the force of air resistance, which is directed opposite to the velocity, is of magnitude 0.85|v|0.85|v| when the parachute is closed and is of magnitude 17|v|17|v| when the parachute is open, where the velocity vv is measured in ft/s. assume that acceleration due to gravity has magnitude 32 ft/s/s; remember that weight is the product of mass and gravitational acceleration. find the speed of the skydiver when the parachute opens. speed is 150.6121788 ft/s find the skydiver's height when the parachute opens. height is 2338.98591 ft find the limiting velocity vlvl after the parachute opens. (think about whether this should be positive or negative.) vl=vl= 7.647 ft/s

Name three different units of energy used to measure heat and describe what type of situations each is usually used.