- #1
Chadlee88
- 41
- 0
Homework Statement
Calculate the flux:
line from (4,6) to (2,6)
using formula: integral v.n dS where v = -yi+xj
n = j
Parametrising:
x = t:
y = 6
Therefore r(t) = ti+6j
r'(t) = i
dS = |r't|dt =>dS = dt
v.n = (-6i+tj) . (j) => t
(As line is going from right to left (4,6) to (2,6))
Lower bound of integration = 4:
Upper bound of integration = 2:
Evaluation:
integral of t dt = t^2/2
therefore Answer is [2^2/2] - [4^2/2] = 2-8 = -6.
The correct answer I'm given is 6 but i don't know where I've gone wrong. could someone please tell me