Ya it is in your syllabus. And ya if you ain't done with the
other topics... this topic should just give up.
As for V(a-b), Va and Vb... you don't have ShingLee TYS meh?
V(a-b) is the velocity of "a" as it APPEARS to "b". Thus "a"
refer to the wind and "b" refer to the cyclist. And the question
say "45 from the north east".
Step 1 (understanding
the information)
So you draw an arrow STANDALONE pointing toward SouthWest AS the
wind COME from the NorthEast.
And the cyclist (b) is moving south... SO YOU DRAW an arrow
ALONE pointing SOUTH.
Now you know the "arrows" for V(a-b) and Vb
Step 2 (Construction
of diagram)
AND YOU NEED TO FIND Va.
Using the formula Va-b = Va -Vb <----- LOOK AT THE
SHINGLEE TYS!!!
Since you NEED to find Va. MAKE IT THE SUBJECT IN THE
EQUATION.
Va = Va-b + Vb
Now JUST PUT THE TIP OF YOUR PEN TO PAPER. DRAW IN THE DIRECTION
OF Vb, STOP, DON'T LIFT YOUR PEN. CONTINUE NOW IN THE DIRECTION OF
Va-b.
LIFT YOUR PEN UP AND LOOK!!! YOU NOW HAVE 2 SIDES OF A TRIANGLE.
THE 3rd SIDE WILL BE your Va.
In my diagram. I represented the apparent velocity (Va-b) AS Va.
The velocity of the cyclist as Vc ( Vb in the formula) and THE
velocity of the wind as Vw( Va in the formula).
FROM HERE ON, IT IS ELEMENTARY MATHEMATICS.
