mass increased as you approach the speed of light correct? what is the max value- infinity or something else depending on the rest mass? basically what im getting at is how would you calculate the increase in mass based on speed? plus what is speed, after all this is relativity. speed relative to the earth which is also rotating in space? would everythig weigh fractionally less if the earth stopped rotating (without affecting gravity) since you would be in less motion relative to the universe?