if we have velocity u along x-axis and velocity v along y-axis then is the resultant of these two will be the change in velocity? if yes why is it so? please explain....

Dear Pooja

resultant velocity will be the vector addition of the two velocities.

Suppose if V_x is 3 and V_y is 4 then V=3i+4j

and magnitude of resultant=√(3²+4²) = 5

if V_x is -3 (negative means velocity is along negative direction of x axis) and V_y is 4 then resultant V=-3i+4j

and magnitude of resultant=√((-3)²+4²)=5

for more details on vector addition see the first chapter in physics book

or follow the link

http://www.askiitians.com/iit-jee-physics/general-physics/addition-and-subtraction-of-vectors.aspx

All the best.                                                           

AKASH GOYAL

AskiitiansExpert-IITD

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Actually the change is not the correct term to be used here.The resultant is the net velocity of the body,which has u and v as its components along x and y axis.Here the velocities u and v are independent,they have no effect on each other(because they are at 90 degrees).The essence of change in any physical dimension is the effect of some other agent which is indespensible.