1. The problem statement, all variables and given/known data Heather and Jerry are standing on a bridge 50\;m above a river. Heather throws a rock straight down with a speed of 20\;m/s. Jerry, at exactly the same instant of time, throws a rock straight up with the same speed. Ignore air resistance. How much time elapses between the first splash and the second splash? 4.08 s 2. Relevant equations 3. The attempt at a solution i already have the answer of 4.08 s, which according to mastering physics, is correct. question is: in solving the equations i was instructed to use a positive g for heather and a negative g for jerry........i don't get this. maybe i did the problem wrong and got the correct answer.