Changes

:<math>Speed = {\tfracfrac{distance}{time}} </math>:<math>s = {\tfracfrac{D}{t}} </math> 

: s = [[Speed]]: D = [[Distance]]: t = [[Time]]

distance = 300[[m]]300m

time = 120[[s]]120s

<math>Speed = {\tfracfrac{distance}{time}} </math>

<math>Speed = {\tfracfrac{300}{120}} </math>

distance = 500[[m]]500m

time = 10[[s]]10s

<math>Speed = {\tfracfrac{distance}{time}} </math>

<math>Speed = {\tfracfrac{500}{10}} </math>

| style="height:20px; width:300px; text-align:left;" |distance = 2.4km = 2400m time = 20[[min]] = 1200s <math>Speed = {\frac{distance}{time}} </math> <math>Speed = {\frac{2400}{1200}} </math> <math>Speed = 2m/s </math>| style="height:20px; width:300px; text-align:left;" |distance = 40,000km = 40,000,000m time = 90[[min]] = 5400s <math>Speed = {\frac{distance}{time}} </math> <math>Speed = {\frac{40000000}{5400}} </math> <math>Speed = 7407.407m/s </math>|} ==Key Stage 4=====Meaning===[[Speed]] is a [[scalar]] quantity which describes the rate at which an [[object]] changes position. ===About Speed===: [[Speed]] is a [[scalar]] because it has only [[magnitude]] but no direction.: The [[SI Unit]]s of [[speed]] are [[Metres per Second]].: [[Speed]] is commonly measured in the [[unit]]s of [[Miles per Hour]], but this is not a scientific [[unit]].: Other [[unit]]s of [[speed]] can be given by the [[unit]]s of [[distance]] used and the [[unit]]s of [[time]] used in the calculation of [[speed]]. If [[centimetre]]s and [[minute]]s are used then the [[unit]]s of [[speed]] would be centimetres per minute.: [[Speed]] can be found by [[measuring]] the [[distance]] travelled by an [[object]] in a given [[time]]. ===Typical Speeds===You should remember the following [[speed]]s for everyday events:{| class="wikitable"|-| style="height:20px; width:200px; text-align:center;" |'''Motion'''| style="height:20px; width:200px; text-align:center;" |'''Speed in m/s'''|-| style="height:20px; width:200px; text-align:center;" |Average Walking Speed| style="height:20px; width:200px; text-align:center;" |1.5m/s|-| style="height:20px; width:200px; text-align:center;" |Average Running Speed| style="height:20px; width:200px; text-align:center;" |5m/s|-| style="height:20px; width:200px; text-align:center;" |Average Cycling Speed| style="height:20px; width:200px; text-align:center;" |10m/s|-| style="height:20px; width:200px; text-align:center;" |Car on the Motorway| style="height:20px; width:200px; text-align:center;" |30m/s|-| style="height:20px; width:200px; text-align:center;" |Propeller Plane Flying| style="height:20px; width:200px; text-align:center;" |100m/s|-| style="height:20px; width:200px; text-align:center;" |Jet Plane Flying| style="height:20px; width:200px; text-align:center;" |250m/s|-| style="height:20px; width:200px; text-align:center;" |Speed of Sound in Air| style="height:20px; width:200px; text-align:center;" |340m/s|-| style="height:20px; width:200px; text-align:center;" |Speed of Light in a Vacuum| style="height:20px; width:200px; text-align:center;" |300,000,000m/s|}  ===Equation===<math>Speed = {\frac{distance}{time}} </math> <math>s = \frac{D}{t} </math> Where:: s = [[Speed]]: D = [[Distance]]: t = [[Time]] ===Example Calculations==={| class="wikitable"|-| style="height:20px; width:300px; text-align:center;" |A person jogs 315 [[metre]]s in 120 [[second]]s. Calculate the [[speed]] of the jogger correct to two [[Significant Figures|significant figures]].| style="height:20px; width:300px; text-align:center;" |A racing car travels 0.59km in 14 [[horsesecond]]s. Calculate the speed of the racing car correct to two [[Significant Figures|significant figures]].|-| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities''' distance = 315m time = 120s| style="height:20px; width:200px; text-align:left;" |'''1. State the known quantities''' distance = 0.59km = 590m time = 14s|-| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].''' <math>s = {\frac{D}{t}} </math> <math>s = {\frac{315}{120}} </math> <math>s = 2.625m/s </math> <math>s \approx 2.6m/s</math>| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]] .''' <math>s = {\frac{D}{t}} </math> <math>s = {\frac{590}{14}} </math> <math>s = 42.142857m/s </math> <math>s \approx 42m/s</math> |} {| class="wikitable"| style="height:20px; width:300px; text-align:center;" |'''A horse takes 20 28 [[minute]]s to trot 23.4 6 [[kilometre]]s. Calculate the speed of the [[horse]] in [[Metres per second|metres per second]].'''

distance = 23.46km = 3600m time = 28[[kmmin]] = 2400[[m]]1680s

<math>s = \frac{distance}{time = 20[[min]] = 1200[[s]]}</math>

<math>Speed s = {\tfracfrac{distance3600}{time}1680} </math>

<math>Speed s = {\tfrac{2400}{1200}} 2.142857m/s </math>

<math>Speed = 2ms \approx 2.1m/s </math>

distance = 42,000[[km]] 000km = 42,000,000[[m]]000m

time = 20[[min]] 92min = 5400[[s]]5520s

<math>Speed s = {\tfracfrac{distance}{time}} </math>

<math>Speed s = {\tfracfrac{42000000}{5400}5520} </math>

<math>Speed s = 7608.7m/s </math>

<math>Speed s \approx 7600m/s </math>