# Mechanics - Forces and Motion

> Source: https://ollybritton.com/notes/a-level/maths/topics/mechanics/forces-and-motion/ · Updated: 2024-08-25 · Tags: school, mechanics, year-1

## See Also
- [Physics - Force and Newtons](https://ollybritton.com/notes/a-level/physics/topics/force-and-newtons/)
- [Mechanics - Friction](https://ollybritton.com/notes/a-level/maths/topics/mechanics/friction/)
- [Mechanics - Forces on Slopes](https://ollybritton.com/notes/a-level/maths/topics/mechanics/forces-on-slopes/)
- [Mechanics - Forces](https://ollybritton.com/notes/a-level/maths/topics/mechanics/forces/)

## Flashcards
### 2021-01-05
##### What is a force diagram??
A diagram showing all the forces acting on an object.

##### What should you draw whenever you have a problem involving forces in Mechanics??
A force diagram.

##### In $\hat{i}$ and $\hat{j}$ notation, what is the value of a resultant force for an object in equilibrium??
$$
0\hat{i} + 0\hat{j}
$$

### 2021-02-02
##### If $$ \left(\begin{matrix} 2+p \\ 5+q \end{matrix}\right) $$ is parallel to $$ \left(\begin{matrix} 1 \\ -2 \end{matrix}\right) $$, what equation could you write in terms of a new variable $k$ to aid in solving??
$$
\left(\begin{matrix} 2+p \\ 5+q \end{matrix}\right) = \left(\begin{matrix} k \\ -2k \end{matrix}\right)
$$

##### If $$ \left(\begin{matrix} 2+p \\ 5+q \end{matrix}\right) = \left(\begin{matrix} 1k \\ -2k \end{matrix}\right)$$ is true, what two equations can you write??
$$
2+p = k \\\\
5+q = -2k
$$

##### $$2+p = k \\ 5+q = -2k$$ How could you rewrite this so it's just in terms of $p$ and $q$??
$$
-2(2 + p) = 5 + q
$$

### 2022-03-28
##### What's the normal procedure for answering a ladder or hinge question??
* Take moments
* Resolve forces

##### How many components of reaction are there at a wall in a ladder question??
$$
1
$$

##### How many components of reaction are there at the hinge??
$$
2
$$

### 2022-05-01
##### Why is the reaction on a smooth surface always perpendicular to the surface??
As the surface is smooth, there is no friction and so the reaction is unchanged.

##### When reading a tricky mechanics question, what is it a good idea to do??
Circle all words like "smooth", "rough", "uniform", etc.

###### Is the reaction force necessarily the resultant force??
No, not if there is friction involved.

### 2022-05-15
##### If a string connecting two particles over a pulley is not actually light, what will be true??
The tensions will no longer be equal.

---
Olly Britton — https://ollybritton.com. Machine-readable index: https://ollybritton.com/llms.txt