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The following surface integral is to be evaluated over a sphere for the given steady velocity vector field F = x i + y j + z k defined with respect to a Cartesian coordinate system having i, j and k as unit base vectors.
∬_S (F · n) dA
where S is the sphere, x² + y² + z² = 1 and n is the outward unit normal vector to the sphere. The value of the surface integral is
- 0
- 2
- 3π/4
- 4
Correct answer: 4
Solution
The surface integral evaluates the flux of the vector field F through the sphere's surface. Since F is a linear function and the sphere is symmetric, the total outward flux can be computed using the divergence theorem, which gives a result of 4 for this specific vector field over the unit sphere.
Related GATE Engineering Mathematics questions
- A vector field p and a scalar field r are given by
p = (2x² - 3xy + z²) î + (2y² - 3yz + x²) ĵ + (2z² - 3xz + x²) k̂
r = 6x² + 4y² - z² - 9xyz - 2xy + 3xz - yz
Consider the statements P and Q.
P: Curl of the gradient of the scalar field r is a null vector.
Q: Divergence of curl of the vector field p is zero.
Which one of the following options is CORRECT?
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