An efficient parcel service wants to speed up its deliveries by dropping parcel into moving tracks. An employee is positioned on the overpass directly above a straight level road to drop the parcels into the trucks at just the right time. One day a delivery van starts from the rest and drive along the road with the fix acceleration of 1/2g. A parcel is released at the accurate instant to land in the van. If the overpass was 30 meter above the van and the van started from the position 100 meter from the point of impact, find how long after the track started did the worker wait before dropping the parcel?