The Basics of Motion - Physics Paper 2

Speed 

• Speed is a scalar quantity. 

• Scalar quantities only have a magnitude (size). 

• Scalar quantities, like speed, do not have a direction. 

Vector 

• Velocity describes an object’s direction as well as its speed. 

• Velocity is a vector quantity because it has a magnitude (or size) and a direction. 

Typical Speeds 

• Typical walking speed is 1.4m/s. 

• Typical running speed is 3.3m/s. 

• Typical speed of a bus in town is 10m/s. 

• Typical speed of a car on the motorway is 31m/s. 

• Typical speed of wind is 6m/s. 

• Typical speed of sound is 340m/s. 

Adding Vectors 

• To add vectors, draw each vector as an arrow one after the other. 

  • The length of the arrow represents the magnitude (size) of a quantity. 

  • The direction of the arrow represents the direction of the vector quantity. 

Vector Addition 

• Jane pushes a table with a force of 10N towards the door, but her brother, Frank tries to stop her by pushing it with a force of 10 N at a right angle to Jane. 

• The effect of these forces is shown above. 

  • Pythagoras’ theorem is used to work out the resultant force. 

  • Resultant Force = √(10…