UBGMXQ-30-1 Engineering Principles for Civil Engineering Flashcards

Flashcards covering vectors, moments, statics, centre of gravity, centroids, worked examples, and module details for UBGMXQ-30-1 Engineering Principles for Civil Engineering.

Who is the module leader for UBGMXQ-30-1 Engineering Principles for Civil Engineering?

Dr.-Ing. Ghada Karaki.

Who are the staff members responsible for lectorials and practical sessions in UBGMXQ-30-1?

Felix Howitt leads the lectorials and Tanvi Singh leads the practical sessions.

What are the three assessment tasks and their respective weightings for UBGMXQ-30-1?

Task 1 consists of E-Assessment tests ($19\%$), Task 2 is a 1000-word practical report ($25\%$), and Task 3 is an in-person 3-hour examination ($56\%$).

What is the minimum passing score required for each individual assessment task in UBGMXQ-30-1?

A student must achieve a score of at least $40\%$ in each task.

What is the fundamental difference between a scalar quantity and a vector quantity?

A scalar quantity has magnitude only (e.g., temperature, mass, distance, energy, time), whereas a vector quantity has both magnitude and direction (e.g., displacement, velocity, force, weight).

How is the direction angle of a vector measured in a two-dimensional system?

The angle is measured anti-clockwise from the positive x-axis.

What does Newton's First Law of Motion state regarding a body's state of motion?

A body will continue in its present state of rest or constant velocity in a straight line unless acted upon by some external force.

How is statics defined in engineering mechanics?

Statics is the study of forces acting on bodies that are either at rest or moving with a constant velocity, such that the bodies have zero acceleration.

How are the resolved force components $F_x$ and $F_y$ calculated for a force $F$ at an angle $\theta$ relative to the horizontal axis?

$F_x = F\cos(\theta)$ and $F_y = F\sin(\theta)$.

What is a moment in mechanics, and what formula gives its magnitude about a point O?

A moment is the measure of the tendency of a force to cause an object to rotate about a specific point or axis, calculated as $M = F \cdot r$, where $r$ is the perpendicular distance from the line of action of the force to point O.

What is the structural difference between a bending moment and a torque?

A bending moment acts around an axis perpendicular to the member's longitudinal axis and causes the element to flex or bend, whereas torque acts around an axis parallel to the longitudinal axis and causes the element to twist.

What is the definition of the centre of gravity (G) of a body?

The centre of gravity is the point around which the resultant moment or torque due to gravity forces vanishes, and through which the total weight of the system acts.

What equation relates weight ($W$), mass ($m$), and gravitational acceleration ($g$)?

$W = m \cdot g$, where $g = 9.81\,m/s^2$.

What is a centroid, and how does it differ from the centre of gravity?

The centroid is the geometric centre of area of a shape, functioning identically to the centre of gravity except that areas are used instead of weights.

What formula defines the position of the centre of gravity $\bar{x}$ for a system of masses along the x-axis?

$\bar{x} = \frac{\sum m \cdot x}{\sum m}$.

Where is the centroid of a triangle of height $d$ located relative to its base?

The centroid is located at a height of $\frac{d}{3}$ from the base.

In a maze, a person walks $800\,m$ west, $700\,m$ south, $600\,m$ east, and $500\,m$ north. What is the resultant displacement magnitude and direction?

The resultant displacement magnitude is $282.84\,m$ at a direction angle of $225^\circ$.

Four concurrent forces act on a body: $15\,N$ at $55^\circ$, $28\,N$ at $110^\circ$, $47\,N$ at $225^\circ$, and $36\,N$ at $305^\circ$. What is their resultant magnitude and angle?

The resultant force has a magnitude of $27.67\,N$ at a direction angle of $240.66^\circ$ (with components $R_x = -13.56\,N$ and $R_y = -24.12\,N$).

A force of $10\,N$ acts at an angle of $50^\circ$ to a line of length $8\,m$ connected to point A. What is the resultant moment about point A?

$M_A = 61.28\,N\cdot m$ acting counter-clockwise (represented as $-61.28\,N\cdot m$).

A vertical T-section has a web of $28\,mm$ width and $42\,mm$ height, a flange of $65\,mm$ width and $12\,mm$ height, and a $15\,mm$ diameter hole centered $27\,mm$ above the base. What is the centroid distance $\bar{y}$ from the base?

$\bar{y} = 32.2\,mm$.

A stepped steel shaft consists of Section A ($20\,mm$ dia, $40\,mm$ long), Section B ($80\,mm$ dia, $40\,mm$ long), Section C ($40\,mm$ dia, $80\,mm$ long), and Section D ($20\,mm$ dia, $60\,mm$ long). What is the distance of its centre of gravity from its left-hand end?

$\bar{x} = 84\,mm$.

What horizontal ($H$) and vertical ($V$) force components correspond to force $F$ at angle $\theta$ as illustrated in this diagram?

The horizontal component is $H = F_x = F\cos(\theta)$ and the vertical component is $V = F_y = F\sin(\theta)$.

What are the centroid positions for the simple geometric sections shown in this diagram?

For a line, rectangle, and circle, the centroid is located at the geometric center; for a triangle of height $d$, it is located at $\frac{d}{3}$ from the base.

What formula for calculating section centroids is derived from the tabular method shown in this diagram?

The distance of the centroid from the chosen axis is given by $\bar{X} = \frac{\sum A \cdot h}{\sum A}$ (or $\bar{Y} = \frac{\sum A \cdot h}{\sum A}$).

What is the calculated distance of the centre of gravity G from the left-hand end for the stepped shaft shown in this diagram?

$\bar{x} = 84\,mm$.