1
GATE CE 1999
MCQ (Single Correct Answer)
+1
-0.3
For the function $$\phi = a{x^2}y - {y^3}$$ to represent the velocity potential of an ideal fluid, $${\nabla ^2}\,\,\phi $$ should be equal to zero. In that case, the value of $$'a'$$ has to be
A
$$-1$$
B
$$1$$
C
$$-3$$
D
$$3$$
2
GATE CE 1996
MCQ (Single Correct Answer)
+1
-0.3
The directional derivative of the function $$f(x, y, z) = x + y$$ at the point $$P(1,1,0)$$ along the direction $$\overrightarrow i + \overrightarrow j $$ is
A
$$1/\sqrt 2 $$
B
$$\sqrt 2 $$
C
$$ - \sqrt 2 $$
D
$$2$$
3
GATE CE 1995
MCQ (Single Correct Answer)
+1
-0.3
The derivative of $$f(x, y)$$ at point $$(1, 2)$$ in the direction of vector $$\overrightarrow i + \overrightarrow j $$ is $$2\sqrt 2 $$ and in the direction of the vector $$ - 2\overrightarrow j $$ is $$-3.$$ Then the derivative of $$f(x,y)$$ in direction $$ - \overrightarrow i - 2\overrightarrow j $$ is
A
$$2\sqrt 2 + 3/2$$
B
$$ - 7/\sqrt 5 $$
C
$$ - 2\sqrt 2 - 3/2$$
D
$$ 1/\sqrt 5 $$
GATE CE Subjects
Fluid Mechanics and Hydraulic Machines
EXAM MAP
Medical
NEET
Graduate Aptitude Test in Engineering
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CBSE
Class 12