# Using integration to determine the area under a curve

Hi, i am doing some course work where i have to determine the flow rate of an air jet at 10D from the nozzle.

Basically I have a graph of velocity against the vertical reading from a manometer and i need to determine volume flow rate by finding the area under this curve. Unfuortunetly i do not understand this technique i am led to believe the trapezoidal or simpsons rule can be used to do this.

The volume flow rate is Q=VA

and the integration used i believe is A=2 $$pi$$ $$\int$$ V rdr

I have looked in my books but this only leads to the confusion. The book suggests i split up all the parts into rectangles and then do the integration for each rectangle then sum them, however using the technique in the book i think all the results will be the same. I do not udnerstand the explanation of the trapezoidal rule and i am not sure how i would apply simpsons rule to this.

This may appear simple but it has me very confused.

Thanks for the help.