Use multiple infrared beams that are aimed across a doorway and positioned so that as a person walks through the doorway some beams are activated.

Suppose water is leaking from a tank through a circular hole of area ah at its bottom. when water leaks through a hole, friction and contraction of the stream near the hole reduce the volume of water leaving the tank per second to cah 2gh , where c (0 < c < 1) is an empirical constant. a tank in the form of a right-circular cone standing on end, vertex down, is leaking water through a circular hole in its bottom. (assume the removed apex of the cone is of negligible height and volume.) (a) suppose the tank is 20 feet high and has radius 8 feet and the circular hole has radius 2 inches. the differential equation governing the height h in feet of water leaking from a tank after t seconds is dh dt = − 5 6h3/2 . if the height of the water is initially 8 feet, how long will it take the tank to empty? (round your answer to two decimal places.)

Aboat travels at 15 m/s in a direction 45° east of north. the boat then turns and travels at 18 m/s in a direction 5° north of east. what is the magnitude of the boat's resultant velocity? round your answer to the nearest whole number. /s what is the direction of the boat's resultant velocity? round your answer to the nearest whole degree. ° north of east

Can any one me on number 4? i do know that it’s not a cause i gotten that wrong on the first try.