Do Now!
description
Transcript of Do Now!
• Can you talk to the person next to you about what we did last lesson?
Do Now!
A reminder
A reminder
Average speed = distance travelled time taken
S tdx
Examples
A man runs 99 m in 11 seconds. What is his speed?
Examples
A man runs 99 m in 11 seconds. What is his speed?
Speed = distance/time = 99/11 = 9 m/s
Another example
A dog runs at a speed of 3 m/s for two minutes. How far does he run?
Another example
A dog runs at a speed of 3 m/s for two minutes. How far does he run?
Distance = speed x time = 3 x 120 = 360 m
Another example!
A car travels at 60 km/h and covers a distance of 300 km. How long did it take?
Another example!
A car travels at 60 km/h and covers a distance of 300 km. How long did it take?
Time = distance/speed = 300/60 = 5 hours
Do now!Can you discuss with the person next to you what we
learnt (hopefully!) last lesson?
Distance against time graphs
distance
time
Let’s go on the corridor!
Let’s quietly and sensibly go in the corridor.
You’ll need a pencil and a
piece of paper.
Distance/time graphDistance /m
0 2 4 6 8 10 12 14 16
Time (slow)/s
0 2.2 4.0 5.6 7.4 9.0 11.0 12.9 14.6
Time (fast)/s
0 1.5 2.0 3.2 4.1 4.9 5.9 7.1 8.0
Distance/m 18 20 22 24 26 28 30 32
Time (slow/s 14.5 17.3 18.9 20.9 23.9
Time (fast)/s 8.4 9.7 10.6 12.1 12.8
distance
time
No movement?
distance
time
No movement
distance
time
Constant speed?
distance
time
Constant speed
distance
time
Constant speed
distance
time
The gradient of this graph gives the speed
Constant speed
distance
time
Δy
Δx
Gradient = Δy/Δx
Constant speed
distance
time
How would the graph look different for a faster constant speed (walking to
Physics)?
Constant speed
distance
time
fast
Constant speed
distance
time
fast
How would the graph look different for a slower constant
speed (walking to French)?
Constant speed
distance
time
fast
slow
Constant speed
distance
time
fast
slow
The gradient of the graph gives
the speed
Let’s go on the corridor!
Quietly and sensibly!
You’ll need a pencil and your
books
Distance/time graph - acceleration
Distance /m
0 2 4 6 8 10 12 14 16 18
Time/s 0 3.5 4.8 6.1 7.2 7.6 8.4 9.1 9.4 9.8
Distance/m 20 22 24 26 28 30 32
Time/s 10.0 10.4 11.2 11.0
Do now!Can you read Mr Porter’s
comments in your books?
Getting faster? (accelerating)
distance
time
Getting faster (accelerating)
distance
time
Examples
distance
time
A car accelerating from rest and then hitting a wall
distance
time
A car accelerating from stop and then hitting a wall
distance
time
Do now! Can you do the worksheet “Distance –
time graphs”?
Write the answers in your books, NOT on
the sheet.
Do now!Can you find
the “Cool Runnings”
results table?
Cool Runnings!
Speed against time graphs
speed
time
Speed against time graphs
speed
time
No movement?
speed
time
No movement
speed
time
Constant speed?
speed
time
Constant speed
speed
time
Constant speed
speed
time
How would the graph look
different for a faster constant
speed?
Constant speed
speed
time
fast
Constant speed
speed
time
fast
How would the graph look
different for a slower constant
speed?
Constant speed
speed
time
fast
slow
Getting faster? (accelerating)
speed
time
Getting faster? (accelerating)
speed
time
Constant acceleration
Getting faster? (accelerating)
speed
time
The gradient of this graph gives the acceleration
Acceleration
speed
time
a = v – u
t
(v= final speed, u = initial speed)
v
u
Acceleration (m/s2)
acceleration = change in speed time taken
a = v – ut
a = acceleration (m/s2)v = final speed (m/s)u = initial speed (m/s)t = time taken (s)
Can you copy this please?
Getting faster? (accelerating)
speed
time
The area under the graph gives the distance travelled
Example:
speed
time
A dog falling from a tall building (no air resistance)
speed
time
A dog falling from a tall building (no air resistance)
speed
time
What does this area represent?
A dog falling from a tall building (no air resistance)
speed
time
Area = height of building
Be careful!
distance
time
speed
time
No movement
distance
time
speed
time
Constant speed
distance
time
speed
time
Area under graph = distance travelled
gradient = speed
Constant acceleration
distance
time
speed
time
Area under graph = distance travelled
Gradient = acceleration =
a = (v-u)/t
Stick them in!
Cool Runnings – the worksheet!
These questions are to be
finished for homework. Due next Friday 25th
September
“Ticket to exit”?!