Create notes on mmme1028 lectures L1.1, L1.2

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---
author: Alvie Rahman
date: \today
tags:
- uni
- nottingham
- mmme1028
- maths
- statics
- dynamics
title: MMME 1028 // Statics and Dynamics
---
# Lecture 1.1, 1.2
### Lecture 1.1 (L1.1) Exercises
Can be found [here](./lecture_exercises/mmme1028_l1.1_exercises_2021-09-30.pdf).
### Lecture 1.2 (L1.2) Exercises
Can be found here [here](./lecture_exercises/mmme1028_l1.2_exercises_2021-10-04.pdf)
## Newton's Laws
1. Remains at constant velocity unless acted on by external force
2. Sum of forces on body is equal to mass of body multiplied by
acceleration
> 1st Law is a special case of 2nd
3. When one body exerts a force on another, 2nd body exerts force
simultaneously of equal magnitude and opposite direction
## Equilibrium
- Body is in equilibrium if sum of all forces and moments acting on
body are 0
### Example
Determine force $F$ and $x$ so that the body is in equilibrium.
![](./images/vimscrot-2021-10-04T09:14:41,378027532+01:00.png)
1. Check horizontal equilibrium
$\sum{F_x} = 0$
2. Check vertical equilibrium
$\sum{F_y} = 8 - 8 + F = 0$
$F = 2$
3. Take moments about any point
$\sum{M(A)} = 8\times{}2 - F(2+x) = 0$
$F(2+x) = 16)$
$x = 6$
## Free Body Diagrams
A free body diagram is a diagram of a single (free) body which shows all
the external forces acting on the body.
Where there are several bodies or subcomponents interacting as a complex
system, each body is drawn separately:
![](./images/vimscrot-2021-10-04T09:23:03,892292648+01:00.png)
## Friction
- Arises between rough surfaces and always acts at right angles to the
normal reaction force ($R$) in the direction to resist motion.
- The maximum value of friction $F$ is $F_{max} = \mu{}R$, where
$\mu{}$ is the friction coefficient
- $F_{max}$ is also known as the point of slip
## Reactions at Supports
There are three kinds of supports frequently encountered in engineering
problems:
![](./images/vimscrot-2021-10-04T09:41:56,080077960+01:00.png)
## Principle of Force Transmissibility
A force can be move dalong line of action without affecting equilibrium
of the body which it acts on:
![](./images/vimscrot-2021-10-04T09:43:04,689667620+01:00.png)
This principle can be useful in determining moments.
## Two-Force Bodies
- If a body has only 2 forces, then the forces must be collinear,
equal, and opposite:
![](./images/vimscrot-2021-10-04T09:44:05,581697277+01:00.png)
> The forces must be collinear so a moment is not created
## Three-Force Bodies
- If a body in equilibrium has only three forces acting on it, then
the lines of actions must go through one point:
![](./images/vimscrot-2021-10-04T09:55:59,773394306+01:00.png)
> This is also to not create a moment
- The forces must form a closed triangle ($\sum{F} = 0$)
## Naming Conventions
| Term | Meaning |
|----------------------|----------------------------------------------------------|
| light | no mass |
| heavy | body has mass |
| smooth | there is no friction |
| rough | contact has friction |
| at the point of slip | one tangential reaction is $F_{max}$ |
| roller | a support only creating normal reaction |
| rigid pin | a support only providing normal and tangential reactions |
| built-in | a support proviting two reaction components and a moment |
## Tips to Solve (Difficult) Problems
1. Make good quality clear and big sketches
2. Label all forces, dimensions, relevant points
3. Explain and show your thought process---write complete equations
4. Follow standard conventions in equations and sketches
5. Solve everything symbolically (algebraicly) until the end
6. Check your answers make sense
7. Don't forget the units