The imaginary line drawn in the fluid in such a way that the tangent to any point gives the direction of motion at that point, is known as _______
- APath line
- BStream lineCorrect
- CSteak line
- DPotential line
Solution
Concept
A stream line is an imaginary line in a fluid flow where the tangent at any point gives the direction of velocity of the fluid particle at that instant.
Step-by-step solution
1. Understand the definition of different lines in fluid kinematics. 2. A line where the tangent drawn at any point gives the direction of motion or velocity vector at that instant is called a stream line. Answer: (B) Stream line
Explanation
Stream lines show the instantaneous flow direction of fluid particles. No fluid can cross a stream line because there is no flow component perpendicular to it.
Why the other options are wrong
A: Path line is the actual path traveled by a single particle over a time interval. C: Streak line is the locus of all particles that have passed through a specific point. D: Potential line is a line along which the velocity potential is constant, intersecting stream lines at right angles.
Shortcut
Remember: Stream line = Tangent gives direction of motion (velocity) at that instant.
Common mistake
Confusing stream lines with path lines, which trace the actual path of a single fluid particle over a period of time.
Correct answer: B) Stream line