1. Basic Concepts in Motion

Seite 1

1. Vehicles do not typically travel at a constant speed

1.1 - Speed

Identify that a typical journey involves speed changes

- In reality, travelling speed changes from instant to instant along a journey

1.2 - Speed

Distinguish between the instantaneous and average speed of vehicles and other bodies

Speed is the rate of change of distance - how fast a distance is covered

Avergage Speed is used to describe how quickly overall a particular distance is covered, calculated by dividing the total distance travelled by the total time spent to cover this distance

Instantaneous Speed is the speed of an object at a particular moment or instant. It is the speed of an object at any given point in time

Constant Speed occurs when an object's speed does not change, ie, acceleration is 0. In this case, the average speed is equivalent to the instantaneous speed

1.3 - Scalar quantities and vector quantities

Distinguish between scalar and vector quantities in equations

Scalar quantity: A quantity that only describes magnitude or size. Examples include distance, speed, volume, mass, length and time

Vector quantity: A quantity that describes magnitude and direction. Examples include displacement, velocity and acceleration

Scalar quantities only have magnitude whereas vector quantities have both magnitude and direction

eg. Distance is scalar - Distance from town A to B is 100km

However displacement is vector - Displacement of town B from A is 100km NE

Seite 2

1.4 - Velocity

Compare instantaneous and average speed with instantaneous and average velocity

Velocity is the rate of change of displacement

It is a vector quantity, while speed is a scalar quantity

This can also be average or instantaneous

Average velocity is the total change of displacement divided by the total change of time - direction is specified

Instantaneous velocity is the change of displacement at a particular moment or instant - direction is specified

1.5 - Velocity

Define average velocity as v=dr/dt