Speed

 
9.1  Speed
 
  Definition  
     
 

The rate at which something moves or operates.

 
 
Speed as a rate:
 
  Definition  
     
 

It is the rate of change of distance with time.

 
   
Formula
   

 
\(\text{Speed} = \dfrac{\text{Distance}}{\text{Time}} \)
   
Uniform and non-uniform speed:
   
Uniform Speed Non-uniform Speed
  • Covers at equal distance in equal interval of time
  • It implies the movement of an object along a straight line with steady speed
  • Similar to the actual speed of the object.
  • The distance-time graph shows a straight line
  • Covers at unequal distance in equal interval of time
  • It implies the movement of an object along a straight line with variable speed
  • Different from the actual speed of the object
  • The distance-time graph shows a curved line

 
Average speed:
   
Formula
   
\(\text{Average speed} = \dfrac{\text{Total distance}}{\text{Total time}}\)
 
  Example   
     
 

A truck travels \(132\text{ km}\) in \(22\text{ hours}\).

What is the speed of the truck?

 
     
 

Answer: 

We’re looking for speed, the distance should be divided by time. 

\(\begin{aligned} \space \text{Speed}&= \dfrac{\text{Distance}}{\text{Time}} \\\\& = \dfrac{132 \space\text{km}}{22 \space \text{h}} \\\\&= 6 \space \text{km/h}. \end{aligned}\)