Q. The pilot of an airplane traveling 180 kilometers an hour wants to drop supplies to flood victims isolated on a patch of land 160 meters below.The supplies should be dropped how many seconds before the plane is directly overhead?

Q. A 2.1 piece of wood slides on the surface. The curved sides are perfectly smooth, but the rough horizontal bottom is 31 long and has a kinetic friction coefficient of 0.25 with the wood. The piece of wood starts from rest 4.0 above the rough bottom. Where will this wood eventually come to rest and For the motion from the initial release until the piece of wood comes to rest, what is the total amount of work done by friction?