Is centre of pressure the same way they represent curl in mathematics ? i.e representation of pressure condensed to a single point? Also,on a tv show,the presenter said this about the air-brakes on a P-28 fighter,"The air-brakes change the centre of pressure thereby allowing the wind-flow to stick at high speeds".What does he mean by this? ASIDE:Since I guess the representation of centre of pressure is pretty similar to curl,could someone please tell me why mathematicians use the gradient to represent curl? As a engineer,I'm more used to seeing exercises where curl is calculated using the position vector 'dr' and then taking the line integrals.How can I prove that the gradient x field=line integral stuff ??? Thanks.