@?mechanics

Flashcards 2022-02-07 Can you use SUVAT in two dimensions?? Yes. Backlinks [[Maths - Syllabus]]S Metadata date: 2022-02-07 12:34 tags: - '@?mechanics' - '@?maths' - '@?year-2' - '@?school' - '@?public' title: Mechanics - Further Kinematics

Flashcards 2021-11-20 What is the formula for the maximum friction?? $$ F_\text{max} = \mu R $$ What is $\mu$ when talking about friction?? The coefficient of friction. What is $\mu$ if a surface is described as “smooth”?? $$ 0 $$ If a block is being pushed with a $10\text{N}$ force but there is a $20\text{N}$ max friction, what will happen?? The block will not move. What is the situation called when a block is being pushed with a $20\text{N}$ force but there is a $20\text{N}$ max friction?

Flashcards 2021-11-20 What is the angle beneath the red block?? $$ 3\text{kg} $$ What is the resultant force in this diagram, assuming no resistive forces?? $$ 3g\sin(30^\circ) $$ What is the resultant force in this diagram?? $$ 2g\sin(20^\circ) - 2 $$ What is the resultant force in this diagram?? $$ 5g\cos(60^\circ) - mg\sin(30^\circ) $$ 2022-01-20 What will happen to the direction of friction for an object moving up a slope but accelerating downwards?? It will flip direction when the object flips direction.

Flashcards Why is it good to carefully choose the point where you take moments?? Because you can ignore the rotational effect of any forces acting at that point. Why is it good to take moments at $R_A$ or $R_C$ here rather than halfway down the rod?? Because you only get 1 unknown. 2021-11-17 If a rigid body is tilting about a pivot, what can you say about the reaction at any other support?? It is zero.

This links heavily to [[Physics - Force and Newtons]]S . 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. What does the force diagram look fora block of weight $W$ being pulled by a force P on a rough horizontal plane?? How would this diagram change if it was a smooth plane?? In $\hat{i}$ and $\hat{j}$ notation, what is the value of a resultant force for an object in equilbrium?

See [[Physics - SUVAT Equations]]S , it’s largely the same. If you have two cars which decelerate the same amount ($a$) over the same distance ($s$), which SUVAT equation can you use?? $$ v^2 = u^2 + 2as $$ Two cars, $A$ and $B$, have a $100ms^{-1}$ and $80ms^{-1}$ velocity respectively. Car $B$ reaches a final velocity of $0ms^{-1}$. Car $A$ reaches a final velocity of $x\, ms^{-1}$. They decelerate the same amount ($a$) over the same distance ($s$).

What is $\hat{i}$?? The unit vector in the x direction. What is $\hat{j}$?? The unit vector in the y direction. What is the unit vector in the x direction?? $$ \hat{i} $$ What is the unit vector in the y direction?? $$ \hat{j} $$ What is $\begin{matrix}-2 \ 3\end{matrix}$ in unit vector form?? $$ -2\hat{i} + 3 \hat{j} $$ What is $4\hat{i} - 2\hat{j}$ in column vector form?? $$ \begin{matrix}4 \ -2\end{matrix} $$ What is the magnitude of displacement?

Forces What is the weight of an object?? The force acting vertically downwards. What is the normal reaction?? The force acting perpindicular from a surface when an object is in contact with the surface. What is the normal reaction the same as?? The weight of an object on a surface. What is the name of the force acting perpindicular from a surface on an object resting on the surface?? The normal reaction. What is friction?? The force which opposed the motion between two rough surfaces.

Models What is a model?? A model is a simplified representation of a physical situation, made by accepting assumptions. What’s an example of a common assumption?? No air resistance Constant gravity Uniform mass What two questions need to be asked when setting up a mathematical model?? What are your assumptions? What are the variables? If the answer presented by a mathematical model is unreasonable, what should be done?? You should reconsider your assumptions.