Resource Description

• Module 1: Kinematics 
• Module 2: Dynamics 
• Module 3: Waves and Thermodynamics 
• Module 4: Electricity and Magnetism

Module 1: Kinematics

Distance and Displacement

Distance is a measure of the total length of the path taken during the change in position of an object. 

• Distance is a scalar quantity. Scalar quantities are those that specify size/magnitude, but not direction. E.g. Distance is 11m 

Displacement is a measure of the change in the position of an object – a straight line between where it started compared to where it finished

• Displacement is a vector quantity. Vector quantities are those that specify a direction as well as magnitude. 
  • E.g. Displacement is 5m north (from original position, even if the total distance travelled is 11m)

Example of Distance vs Displacement: A runner going around a 400m circular race track. Even if the runner runs a distance of 400m around the racetrack, since they end up at the start/finish line, their total displacement is 0m.  

Speed and Velocity

Speed is the rate at which distance is covered per unit of time – it is a scalar quantity

There are two types:

Instantaneous speed

• Speed of an object at a particular moment

Average speed

• The average speed of an object tells us generally about the speed over a given time 
  • For example, a car that makes a 120 kilometre journey from one side of the city to the other in two hours will have an average speed of 60km/h.
  • This doesn’t mean that the car is constantly travelling at exactly 60 km/h for the whole trip

Distance = Speed x Time

 

Velocity is a measure of the rate of change in position/displacement in a given direction – it is a vector quantity

• It is the measure of speed in a given direction – E.g. wind speed
• Velocity has magnitude as well as direction

• If a ball is thrown up in the air and falls back straight down, it has a displacement of zero, so the velocity of the ball is zero

Displacement = Velocity x Time

Speed vs Velocity example:

Measuring Speed

• Stopwatch 
• Ticker Timer 
• Radar guns, based on change in radio frequency of the waves of a moving car (instantaneous speed)
• Laser guns, based on reflected light pulses of target moving vehicle (instantaneous speed)
• Digitectors (amphometers), based on sound of a moving vehicle recorded by two parallel cables (average speed)