Since trough is 10 ft long and water is filled at the rate of 12ft3/min. We can calculate the rate of water filled with respect to area:
= 12 / 10 = 1.2ft2/min
As the water level rises, so does the water surface, or the bottom side of the isosceles triangles. In fact we can calculate the bottom side when the trough is half foot deep:
= 3 / 2 = 1.5 ft
The rate of change in water level would be the same as calculating the height of the isosceles triangles knowing its base
The physical changes are you are breaking down the food u eat and the chemical changes are when the enzymes in your stomach break down the food that you have already eaten