Cards In This Deck

• $\text{When a particle is dropped from rest, what values should you assign to }u\text{ and }a\text{ (assuming downwards is positive)?}$
  $$\begin{gathered} \text{* }u=0{ms}^{-1} \\ \text{* }a=9.8{ms}^{-2} \end{gathered}$$
• $\text{First step to solve a vertical motion problem where a ball is projected upwards from a point }X\text{ above the ground?}$
  $$\begin{gathered} \text{Define a positive direction (usually upwards or downwards).} \\ \text{If taking upwards as positive:} \\ \text{* }u=+\text{ value} \\ \text{* }a=g=-9.8{ms}^{-2} \\ \text{* Displacement }s\text{ is measured from }X\text{ (so ground level is }s=-h\text{).} \end{gathered}$$
• $$\begin{gathered} \text{True or False?} \\ \text{At the greatest height reached by a particle projected vertically upwards, its acceleration is zero.} \end{gathered}$$
  $$\begin{gathered} \text{❌ False} \\ \text{✅ Correct Answer: Acceleration is }g=9.8{ms}^{-2}\text{ (downwards).} \\ \text{At the greatest height, the velocity is zero (}v=0\text{), but gravity is still acting on the object, so acceleration remains constant.} \end{gathered}$$
• $$\begin{gathered} \text{True or False?} \\ \text{If a question states an object has a mass of }10kg\text{, its weight is }10kg\text{.} \end{gathered}$$
  $$\begin{gathered} \text{❌ False} \\ \text{✅ Correct Answer: Weight is a force measured in Newtons (}N\text{). } \\ W=mg=10\times 9.8=98N \end{gathered}$$
• $$\begin{gathered} \text{A car travels from London to Edinburgh (}600km\text{). } \\ \text{Can we model the car as a particle?} \end{gathered}$$
  $$\begin{gathered} \text{Yes.} \\ \text{The distance travelled is much larger than the dimensions of the car, so its size and rotation are negligible.} \end{gathered}$$
• $$\begin{gathered} \text{True or False?} \\ \text{The standard SI unit for mass in mechanics is the gram (}g\text{).} \end{gathered}$$
  $$\begin{gathered} \text{❌ False} \\ \text{✅ Correct Answer: Kilogram (}kg\text{)} \end{gathered}$$
• $$\begin{gathered} \text{True or False? } \\ \text{A lamina is a 3D object, so you must consider the distance to the centre of mass in three dimensions.} \end{gathered}$$
  $$\begin{gathered} \text{❌ False} \\ \text{✅ Correct: A lamina is modelled as a 2D object (a plane) whose thickness can be ignored.} \end{gathered}$$
• $\text{When a mathematical model’s predictions do not match experimental data, what is the standard procedural step?}$
  $\text{Refine the model.}$
• $$\begin{gathered} \text{A car is being parked in a small garage. } \\ \text{Can we model the car as a particle?} \end{gathered}$$
  $$\begin{gathered} \text{No.} \\ \text{The dimensions of the car are significant relative to the space (the garage). Rotational forces and size cannot be ignored.} \end{gathered}$$
• $$\begin{gathered} \text{True or False? } \\ \text{When a question states a rod is ’uniform’, it means the rod has negligible thickness.} \end{gathered}$$
  $$\begin{gathered} \text{❌ False} \\ \text{✅ Correct: ’Uniform’ means the mass is evenly distributed, so the weight acts exactly at the geometric midpoint.} \end{gathered}$$
• $\text{When modelling a ladder resting against a wall, we often treat it as a rod. What properties does this assumption imply?}$
  $$\begin{gathered} \text{1. Mass is concentrated along a line (one-dimensional).} \\ \text{2. It is rigid (does not bend or buckle).} \\ \text{3. It has no thickness.} \end{gathered}$$
• $$\begin{gathered} \text{True or False?} \\ \text{Unless told otherwise, you should use }g=9.81{ms}^{-2}\text{ for the acceleration due to gravity in M1.} \end{gathered}$$
  $$\begin{gathered} \text{❌ False} \\ \text{✅ Correct Value: }g=9.8{ms}^{-2} \\ \text{The Edexcel M1 specification requires using }g=9.8\text{. Using }9.81\text{ might lead to rounding errors in the final answer.} \end{gathered}$$
• $\text{What does modelling an object as a Uniform Body imply about its weight?}$
  $\text{The weight acts through the geometric centre (centre of mass) of the body.}$
• $$\begin{gathered} \text{True or False?} \\ \text{If a model assumes ’air resistance is negligible’, the object will have constant velocity.} \end{gathered}$$
  $$\begin{gathered} \text{❌ False} \\ \text{✅ Correct Answer: It implies no resistive force slows it down, but gravity (}g\text{) or other forces (engines, tension) still cause acceleration.} \end{gathered}$$
• $\text{What is the mathematical consequence of modelling a string as inextensible?}$
  $\text{The magnitude of acceleration is the same for objects connected by the string.}$
• $\text{What is the mathematical consequence of modelling a pulley or surface as smooth?}$
  $\text{There is no friction.}$
• $\text{In a problem involving a ’light smooth pulley’, what two assumptions can you make?}$
  $$\begin{gathered} \text{1. Light: The pulley has no mass (ignore gravity acting on the pulley itself unless asked for force on axle).} \\ \text{2. Smooth: The tension in the string is the same magnitude on both sides of the pulley.} \end{gathered}$$
• $\text{What is the mathematical consequence of modelling a string (or pulley) as light?}$
  $\text{The tension is the same at both ends of the string (or on either side of the pulley).}$
• $$\begin{gathered} \text{A smooth bead is threaded onto a string. } \\ \text{What can we say about the tension in the string on either side of the bead?} \end{gathered}$$
  $\text{The tension is the same on both sides.}$
• $$\begin{gathered} \text{True or False?} \\ \text{If a light inextensible string passes through a smooth bead, the tension in the string is the same on both sides of the bead.} \end{gathered}$$
  $$\begin{gathered} \text{✅ True} \\ \text{Because the bead is smooth, it cannot exert a tangential force on the string to change the tension. Therefore, magnitude }T\text{ is constant throughout the single string.} \end{gathered}$$