MCQOPTIONS
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MCQOPTIONS
This section includes 10 Mcqs, each offering curated multiple-choice questions to sharpen your Fluid Mechanics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
If U∞ = free stream velocity, u = velocity at y, and δ = boundary layer thickness, then in a boundary layer flow, the momentum thickness θ is given by |
| A. | \(\theta = \mathop \smallint \limits_0^\delta \frac{u}{{{U_\infty }}}\left( {1 - \frac{u}{{{U_\infty }}}} \right)dy\) |
| B. | \(\theta = \mathop \smallint \limits_0^\delta \frac{u}{{{U_\infty }}}\left( {1 - \frac{{{u^2}}}{{U_\infty ^2}}} \right)dy\) |
| C. | \(\theta = \mathop \smallint \limits_0^\delta \frac{{{u^2}}}{{U_\infty ^2}}\left( {1 - \frac{u}{{{U_\infty }}}} \right)dy\) |
| D. | \(\theta = \mathop \smallint \limits_0^\delta \left( {1 - \frac{u}{{{U_\infty }}}} \right)dy\) |
| Answer» B. \(\theta = \mathop \smallint \limits_0^\delta \frac{u}{{{U_\infty }}}\left( {1 - \frac{{{u^2}}}{{U_\infty ^2}}} \right)dy\) | |
| 2. |
A block of 2 kg slides on a parallel surface at a speed of 4 m/s. It falls on an unpressed spring and presses it until the block is completely motionless. The amount of kinetic friction is 15 N and the spring constant is 10,000 N/m. Spring presses with _____. |
| A. | 5.5 m |
| B. | 8.5 m |
| C. | 5.5 cm |
| D. | 8.5 cm |
| Answer» D. 8.5 cm | |
| 3. |
For fully developed laminar flow through a circular pipe with Reynolds number Re the friction factor is |
| A. | Inversely proportional to Re |
| B. | Proportional to Re |
| C. | Proportional to square of Re |
| D. | Independent of Re |
| Answer» B. Proportional to Re | |
| 4. |
A nozzle is fitted at the end of a pipe of length 300 m and of diameter 10 cm for transmitting water. What is the diameter of the nozzle considering maximum transmission of power through the nozzle (f = 0.009) |
| A. | 2.6 cm |
| B. | 2.5 cm |
| C. | 2.4 cm |
| D. | 2.7 cm |
| Answer» B. 2.5 cm | |
| 5. |
If x is the distance measured from the leading edge of a flat plate, the laminar boundary layer thickness varies as |
| A. | \(\frac{1}{x}\) |
| B. | \({x^{\frac{4}{5}}}\) |
| C. | \(x^2\) |
| D. | \({x^{\frac{1}{2}}}\) |
| Answer» E. | |
| 6. |
For laminar flow over a flat plate, the thickness of the boundary layer at a distance from the leading edge is found to be 5 mm. The thickness of the boundary layer at a downstream section, which is at twice the distance of the previous section from the leading edge, will be |
| A. | 10 mm |
| B. | \(5\sqrt 2 mm\) |
| C. | \(\frac{5}{{\sqrt 2 }}mm\) |
| D. | 2.5 mm |
| Answer» C. \(\frac{5}{{\sqrt 2 }}mm\) | |
| 7. |
An incompressible fluid flows over a flat plate with zero pressure gradient. The boundary layer thickness is 1 mm at a location where the Reynolds number is 1000. If the velocity of the fluid alone is increased by a factor of 4, then the boundary layer thickness at the same location, in mm will be |
| A. | 4 |
| B. | 2 |
| C. | 0.5 |
| D. | 0.25 |
| Answer» D. 0.25 | |
| 8. |
A boundary is known as hydrodynamically smooth if: |
| A. | \(\frac{K}{\delta}=0.3\) |
| B. | \(\frac{K}{\delta}>0.3\) |
| C. | \(\frac{K}{\delta}<0.25\) |
| D. | \(\frac{K}{\delta}=0.5\) |
| Answer» D. \(\frac{K}{\delta}=0.5\) | |
| 9. |
A fluid is flowing over a flat plate. At a distance of 8 cm from the leading edge, the Reynolds number is found to be 25600. The thickness of the boundary layer at this point is |
| A. | 1.5 mm |
| B. | 2.5 mm |
| C. | 4.0 mm |
| D. | 5.0 mm |
| Answer» C. 4.0 mm | |
| 10. |
Flow separation in flow past a solid object is caused by |
| A. | A reduction of pressure to vapour pressure |
| B. | A negative pressure gradient |
| C. | A positive pressure gradient |
| D. | The boundary layer thickness reducing to zero. |
| Answer» D. The boundary layer thickness reducing to zero. | |