Jack and Jill are on two different floors of their high rise office building and looking out of their respective windows. Jack sees a flower pot go past his window ledge and Jill sees the same pot go past her window ledge a little while later. The time between the two observed events was 4.0 s. Assume air resistance is negligible. (a) If the speed of the pot as it passes Jill's window is 60.0 m/s, what was its speed when Jack saw it go by