Time Distance Speed

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Time Distance Speed
Calculating Speed
Converting Hour Minutes to Decimal Time vice versa
Speed Graphs
Calculating Time
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Calculating Distance
Time Distance Graphs
Time, Distance and Speed Problems
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Starter Questions
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Average Speed
Working Out Average Speed
Learning Intention
Success Criteria

1. Know the speed formula.

1. To explain how to work out simple speed
calculations using the speed formula.
2. Use the formula to work out simple speed
calculations.
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Average Speed
300
The straight line is the average speed for the
journey
White line is actual speeds during journey
200
Distance in miles
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In this chapter we will be dealing with average
speed
(T)
0
4
3
2
1
5
Write down an equation connecting Speed Distance
and Time
From experiments we find that k 1
Average Speed
The connection
Question It is well known that speed is
directly proportional to distance and
inversely proportional to time.
S a
S a D
S
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S
6
If distance is in metres and time in seconds then
speed is in metres per second
If distance is in miles and time in hours then
speed is in miles per hour
Units MUST Agree
Very Important Units must be consistent i.e. The
units of all three variables MUST agree.
If distance is in kilometres and time in hours
then speed is in kilometres per hour
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If distance is in centimetres and time in seconds
then speed is in centimetres per second
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Average Speed
Working Out Speed
Imagine you sailed 45 kilometres between two
islands and it took 3 hours.
In 3 hours you travel
45 km
In 1 hour you travel
45 3 15 km
This means your average speed is
15km/hr
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Can you guess what the formula is
in symbols
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Be careful with the units !
Average Speed
Working Out Speed
For each set of values calculate the average speed
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Average Speed
Ex2.1 Q1 Q9 Ch9 (page 162)
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Starter Questions
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Hrs Mins to Decimal Time
Converting Hrs Mins to Decimal Time
Learning Intention
Success Criteria
1. Know that decimal time MUST be used in
formulae.
1. To show how to convert hours and minutes to
hours ONLY (decimal time) and vice versa.
2. Convert from hours and mins to hours ONLY
(decimal time) and vice versa
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Hrs Mins to Decimal Time
Converting Hrs Mins to Decimal Time
You should already know
Example 1
48 minutes to decimal is
0.8 hr
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2.25 hr
Example 2
2hr 15 minutes to decimal is
To change minutes to decimal hours divide
minutes by 60
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Hrs Mins to Decimal Time
Converting Decimal Time to Hrs Mins
To change decimal time to minutes multiply the
decimal part by 60
Example 1
0.7 hrs to minutes is
42 mins
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3.4 hrs to hours and minutes is
Example 2
3 hrs 24 mins
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What Goes In The Box ?
We must use decimal time when using speed formula
Convert these hours and minutes to hours only
mins 60
1hr 12mins
3hrs 6mins
9 hrs 36mins
After using the formula we must convert our
answer back to hours and minutes
1.2 hrs
3.1 hrs
9.6 hrs
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Convert these hours to hours and minutes
mins x 60
8.9 hrs
1.4 hrs
3.7 hrs
3hrs 42mins
8hrs 54mins
1hr 24mins
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Time Distance Speed
Mixed Problems
Example 1 Daniel drove from his house to the
London, a distance of 495 miles. It took him
8hrs 15mins. What was his average speed?
Working
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Time MUST be in decimal hours
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Average Speed
Converting Hrs Mins to Decimal Times
Now try Ex2.2 Ch9 (page 164)
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Starter Questions
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Speed Graphs
Interpreting Speed Graphs
Learning Intention
Success Criteria
1. Recognise the important features of a speed
graph.
1. To show how to interpret speed graphs by
looking at it slopes.
2. Interpret and complete speed graphs
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Match the statement with the correct letter
Average Speed
f
f
Speed of car
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d
d
b
b
e
e
a
a
c
c
0
4
3
2
1
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Complete the speed graph for the journey
described.
Average Speed
Car passes A at steady speed
Car passes B at same steady speed
Car stops at C
Car start again and reaches same steady speed
through D
Speed of car
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D
C
B
A
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Speed Graphs
Now try Ex3.1 Ch9 (page 165)
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Starter Questions
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Time
Working Out Time
Learning Intention
Success Criteria

• Know the time formula. And
• the importance of units.

1. To explain how to work out simple time
calculations using the time formula.
2. Use the formula to work out simple time
calculations.
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Time
Working Out Time
Use your algebra skills to rearrange the average
speed equation to get an equation for Time.
Multiply each side by T
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Divide each side by S
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Time
Working Out Time Non- Algebra
Imagine you flew 800 miles to Paris and the
average speed of the plane was 200 miles/hr.
To travel 200 miles takes 1 hour
To travel 800 miles takes
800 200 4 hours
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Can you guess what the formula is
in symbols
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Starter Questions
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Remember answer in hours minutes and seconds were
appropriate
Time
Working Out Time
For each set of values calculate the time
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Time
Working Out Time Non- Algebra
Example A car travels 240 miles at an average
speed of 55 mph. How long did it take to
the nearest minute.
0.36 x 60 21.6mins Round to 22mins
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Time
Working Out Time
Now try Ex 4.1 Ch9 (page 167)
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Starter Questions
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Distance
Working Out Distance
Learning Intention
Success Criteria

1. Know the distance formula.

1. To explain how to work out simple distance
calculations using the distance formula.
2. Use the formula to work out simply distance
calculations.
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Distance
Working Out Distance
Use your algebra skills to rearrange the Time
equation to get an equation for Distance.
Multiply each side by T
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Distance
Working out Distances
Imagine you were travelling in a train at a
steady speed of 80km/hr.
In 1 hour you travel
80 x 1 80 km
In 2 hours you travel
80 x 2 160 km
In 3 hours you travel
80 x 3 240 km
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Can you guess what the formula is
in symbols
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Be careful with the units !
Distance
Working Out Distance
For each set of values calculate the distance
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Distance
Working Out Distance
Example A bus travels at an average speed of 70
mph. How far did it travel in
3hours 36 minutes.
First convert to decimal hours 36mins 60 0.6
hours
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Distance
Working Out Distance
Now try Ex 5.1 Ch9 (page 168)
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Starter Questions
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Time Distance Graph
Interpreting Time Distance Graphs
Learning Intention
Success Criteria
1. Understand the term interpret.

• To interpret
• Time Distance Graphs.

• Understand that the speed can be calculated from
  the
• Time - Distance Graph.

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Distance Time Graphs
Interpreting Time Distance Graphs
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Distance Time Graphs
Keypoints
Steeper the slope faster the speed
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Horizontal line stopped
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Distance Time Graphs
Now try Ex 6.1 6.2 Ch9 (page 170)
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Starter Questions
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Time Distance Speed
Mixed Problems
Learning Intention
Success Criteria
1. Know and remember triangle method for
distance, speed time problems.
1. To show the triangle method of remembering
the distance, speed and time formulae.
2. Apply triangle method to mixed problems.
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Careful with time units you must work in decimal
time and convert back at the end.
Time Distance Speed
Mixed Problems
D
S
T
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Simple way to remember the 3 formulae !
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Time Distance Speed
Mixed Problems
Example 1 Daniel drove from his house to the
Blackpool, a distance of 135 miles. It took him
2hrs 15mins. What was his average speed?
Time MUST be in hours format
Working
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Time Distance Speed
Mixed Problems
Example 2 A racing car travelled at 50 km/hr.
What is the distance covered in 6 hours 30mins
?
Working
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Time Distance Speed
Mixed Problems
Example 1 How long did the bus journey take if
it travelled a total distance of 60 km at and an
average speed of 40 km/hr.
Working
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Time Distance Speed
Mixed Problems
Now try Ex 7.1 7.2 Ch9 (page 174)
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