OCR MEI Further Mechanics Major 2019 June — Question 2 4 marks

Exam BoardOCR MEI
ModuleFurther Mechanics Major (Further Mechanics Major)
Year2019
SessionJune
Marks4
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicDimensional Analysis
TypeDerive dimensions from formula
DifficultyModerate -0.5 This is a straightforward dimensional analysis problem requiring students to rearrange the given formula and substitute known dimensions. While it requires understanding that R is dimensionless and knowing standard dimensions (density, velocity, length), it's a mechanical application of dimensional analysis with no conceptual subtlety or multi-step reasoning—easier than average but not trivial.
Spec6.01a Dimensions: M, L, T notation

The Reynolds number, \(R\), is an important dimensionless quantity in fluid dynamics; it can be used to predict flow patterns when a fluid is in motion relative to a surface. The Reynolds number is defined as $$R = \frac{\rho ul}{\mu},$$ where \(\rho\) is the density of the fluid, \(u\) is the velocity of the fluid relative to the surface, \(l\) is the distance travelled by the fluid and \(\mu\) is the viscosity of the fluid. Find the dimensions of \(\mu\). [4]

Question 2:
AnswerMarks
2ML 3
uLT 1
ul  ML3  LT1  L
AnswerMarks
ML 1T 1B1
B1
M1
A1
AnswerMarks
[4]1.2
1.2
1.1
AnswerMarks
1.1
Rearrange correctly to make the
subject and use the fact that R is
dimensionless and substitute their 
and u
1s 1
AnswerMarks
SC: B2 for kg mCondone lower case
Question 2:
2 | ML 3
uLT 1
ul  ML3  LT1  L
ML 1T 1 | B1
B1
M1
A1
[4] | 1.2
1.2
1.1
1.1 | 
Rearrange correctly to make the
subject and use the fact that R is
dimensionless and substitute their 
and u
1s 1
SC: B2 for kg m | Condone lower case
The Reynolds number, $R$, is an important dimensionless quantity in fluid dynamics; it can be used to predict flow patterns when a fluid is in motion relative to a surface.

The Reynolds number is defined as $$R = \frac{\rho ul}{\mu},$$

where $\rho$ is the density of the fluid, $u$ is the velocity of the fluid relative to the surface, $l$ is the distance travelled by the fluid and $\mu$ is the viscosity of the fluid.

Find the dimensions of $\mu$. [4]

\hfill \mbox{\textit{OCR MEI Further Mechanics Major 2019 Q2 [4]}}