When some stars use up their fuel, they undergo a catastrophic explosion called a supernova. this explosion blows much or all of a star's mass outward, in the form of a rapidly expanding spherical shell. as a simple model of the supernova process, assume that the star is a solid sphere of radius r that is initially rotating at 2.4 revolutions per day. after the star explodes, find the angular velocity, in revolutions per day, of the expanding supernova shell when its radius is 4.3r. assume that all of the star's original mass is contained in the shell.

Choose the most likely outcome of this scenario: jen decided to go bike riding without a helmet. while no one is around during her ride, she is thrown from her bike when her wheel goes into a pothole. she is not injured, but she is terrified to get back on her bike. what happens next? a. her physical health is affected even though she wasn't hurt. b. her mental and emotional health are affected because she is afraid to get back on her bike. c. her social health is affected because she is worried her friends saw the fall. d. her overall health is not affected at all by her fall.

(a) calculate the number of electrons in a small, electrically neutral silver pin that has a mass of 10.0 g. silver has 47 electrons per atom, and its molar mass is 107.87 g/mol. (b) imagine adding electrons to the pin until the negative charge has the very large value 1.00 mc. how many electrons are added for every 109 electrons already present

Which scientist was the first to propose the heliocentric model of the universe? a. aristotle b. isaac newton c. galileo galilei d. nicolaus copernicus