Acceleration Notes (Units and Quantities)

Scalars and Vectors  

- Scalars: Quantities with only size (magnitude) and no direction. Scalars are always positive.  

  - Examples: distance, speed, mass, energy.  

- Vectors: Quantities with both magnitude and direction. They can have positive or negative components.  

  - Examples: displacement, velocity, acceleration, force/weight, momentum.  

Key Definitions  

- Displacement: Distance moved in a given direction from a starting point.  

- Velocity: Speed in a given direction; displacement per unit time.  

- Acceleration: Rate of change of velocity with respect to time.  

SI Base Units  

Mechanics relies on internationally standardised SI units:  

- Length (displacement): metre (m).  

- Time: second (s).  

- Mass: kilogram (kg).  

Derived Units  

Many physical quantities are combinations of SI base units:  

- Speed / Velocity:  

  velocity = distance/time = m/s

- Acceleration: 

  acceleration = velocity/time = m/s^2 

- Force / Weight:

  F = m x a = kgm/s^2 = N (newton)