A box is put on a scale which is adjusted to read zero, when the box is empty. A stream of pebbles is then poured into the box from a height h above its bottom at a rate of n pebbles. Each pebble has a mass m. If the pebbles collide with the box such that they immediately come to rest after collision, the scale reading at time t after the pebbles begin to fill the box is

Answer

`{ sqrt((2gh) + gt))}`