Sally finds herself stranded on a frozen pond so slippery that she can't stand up or walk on it. to save herself, she throws one of her heavy boots horizontally, directly away from the closest shore. sally's mass is 60 kg, the boot's mass is 5 kg, and sally throws the boot with speed equal to 30 m/s. a) what is sally's speed immediately after throwing the boot? b) where is the center of mass of the sally-boot system, relative to where she threw the boot, after 10 s? c) how long does it take sally to reach the shore, a distance of 30 m away from where she threw the boot? for all parts, assume the ice is frictionless.