2.1C Acceleration
Transcript of 2.1C Acceleration
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Acceleration = change invelocitytime
Acceleration = rate of change invelocity
a = acceleration
vf= final velocity
vi= initial
velocity
a = Vf - Vi
t
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Acceleration- has
direction, just like
velocity.
Acceleration is aVECTOR (it has both amagnitude and a direction).
The roller coaster
accelerates bothbecause its speed
changes and its
direction
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For its velocity to change, anobject must accelerate.
An object accelerateswhenever its speed
speed or
directiondirection or bothboth change.
So this means.
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An object moving in a circle at
constant speed is alwaysaccelerating (changing direction).
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How can you accelerate at a constantspeed?
Acceleration at constant speedAcceleration at constant speed
Its like gravity. An objects
velocity gets faster every second,but it gets faster at the samerate.
Objects accelerate toward theearth at a rate of 9.8 m/s2. Inother words they fall 9.8m/s
faster every second.
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O p o s i t i v e d i r e c t i o n
0 . 4 m 0 . 7 m 1 . 0 m 1 . 3 m
t = 0 s t = 1 s t = 2 s t = 3 s t = 4 s
An object is moving with uniform acceleration.
Its positions at one-second interval are shown below.
distance traveled in
the first second
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O p o s i t i v e d i r e c t i o n
0 . 4 m 0 . 7 m 1 . 0 m 1 . 3 m
t = 0 s t = 1 s t = 2 s t = 3 s t = 4 s
An object is moving with uniform acceleration.
Its positions at one-second interval are shown below.
distance traveled in
thesecond second.
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O p o s i t i v e d i r e c t i o n
0 . 4 m 0 . 7 m 1 . 0 m 1 . 3 m
t = 0 s t = 1 s t = 2 s t = 3 s t = 4 s
An object is moving with uniform acceleration.
Its positions at one-second interval are shown below.
distance traveled in
thethird second
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O p o s i t i v e d i r e c t i o n
0 . 4 m 0 . 7 m 1 . 0 m 1 . 3 m
t = 0 s t = 1 s t = 2 s t = 3 s t = 4 s
An object is moving with uniform acceleration.
Its positions at one-second interval are shown below.
distance traveled in
thefourth second
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O p o s i t i v e d i r e c t i o n
0 . 4 m 0 . 7 m 1 . 0 m 1 . 3 m
t = 0 s t = 1 s t = 2 s t = 3 s t = 4 s
An object is moving with uniform acceleration.
Its positions at one-second interval are shown below.
0.4 , 0.7 , 1.0 , 1.3 is an arithmetic progression with a
common difference 0.3.
This is an important characteristic of motion with
uniform acceleration.
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ACCELERATIONAcceleration is the change in speed in an object in a period of
time.
change invelocity (m/s)
acceleration
(m/s/s)
Where do the units come from?
a = v t
a = m/s s
a = m/s/s=m/s2
It takes a cyclist 20 secondsto go from
a standing start to 14m/s.
What is their acceleration?
What is 14m/s in km/hr?
a = v/t a = 14m/s / 20s a = 0.7ms-2
= 14 60s 60min 1000m
= 50.4km/hr
v
a t
change intime (s)
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Acceleration
A cyclist accelerates from 0 to 10m/s in 5 seconds. What is heracceleration?
A ball is dropped and accelerates downwards at a rate of 10m/s2
for 12 seconds. How much will the balls velocity increase by? A car accelerates from 10 to 20m/s with an acceleration of 2m/s2.
How long did this take?
A rocket accelerates from 1,000m/s to 5,000m/s in 2 seconds.What is its acceleration?
Acceleration = change in velocity (in m/s)
(in m/s2) time taken (in s)
V
TA
SPEED/TIME GRAPHS
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SPEED/TIME GRAPHS
Time (sec)
10 20 30
Speed
(m/s)
4
8
Using the speed/time graph:
3. What distance is covered in part 1?
4. What is the total distance covered?
d = v t
d = 4m/s 10s
d = 40 m
Part 1 = 40m
Part 2 = 0m
Part 3 = 0m
Part 5 = v t = 8m/s 10 s = 80m
Part 4 = v t = 8m/s 5s = 20m
Total = 40 + 80 + 20 =140m
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ACCELERATION QUESTIONSWhat would these look like on a speed/time graph?
1. stopped
2. slow
3. fast
4. accelerating
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Velocity-time graphs
80
60
40
20
010 20 30 40 50
Velocity
m/s
T/s
1) Upwards line =
Constantacceleration
2) Horizontal line =
Constant velocity
3) Upwards line =
constant accel,slower velocity
4) Downward line =constant accel
opposite direction
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80
60
40
20
0
1) How fast was the object going after 10 seconds?
2) What is the acceleration from 20 to 30 seconds?
3) What was the deceleration from 30 to 50s?
4) How far did the object travel altogether?
10 20 30 40 50
Velocity
m/s
T/s
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Which car (red, green, or blue) experiences the greatest acceleration?
Blue car has the greatest acceleration
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Match the car to the graphMatch the car to the graph
Match the car tothe appropriategraph line.
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MORE RESOURCES
http://www.glenbrook.k12.il.us/GBSSCI/PH
http://www.fearofphysics.com/Xva/xva.html
http://www.quia.com/rr/121411.html?AP_ra http://www.physics4kids.com/files/motion_v
http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/1DKin/U1L1d.htmlhttp://www.fearofphysics.com/Xva/xva.htmlhttp://www.quia.com/rr/121411.html?AP_rand=1991654762http://www.physics4kids.com/files/motion_velocity.htmlhttp://www.physics4kids.com/files/motion_velocity.htmlhttp://www.quia.com/rr/121411.html?AP_rand=1991654762http://www.fearofphysics.com/Xva/xva.htmlhttp://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/1DKin/U1L1d.html