Transcript Acceleration - salibiscience
Slide 1
zoom zoom
ACCELERATION
Slide 2
ACCELERATION TERMS
Acceleration (a)– the rate of change of velocity
(can be +, -, or centripetal)
Deceleration– only negative acceleration
(slowing down)
Centripetal Acceleration– acceleration that
occurs when changing direction (turning)
Freefall– objects falling due to gravity
Force is what you feel when you accelerate
Slide 3
3 WAYS TO ACCELERATE
Since acceleration is a change in velocity and
velocity has 2 parts
We can accelerate by
Changes
1.
2.
in speed
Speed up (+ acceleration)
Slow down (- acceleration)
Changing
3.
Direction
Turning
Changing
both speed and direction
Slide 4
YOUR SPEEDOMETER – THE KEY TO ACCEL
We don’t see
acceleration of an
object well with our eyes
But if we look at a
speedometer we can
see speed change.
Acceleration is a picture
of what your
speedometer is doing
Slide 5
SLOW ACCELERATION
FAST(ER) ACCELERATION
ACCELERATION IS A PIC OF YOUR SPEEDO
Slide 6
THE VARIABLES
Speed ( or velocity)is the
dependent variable
Time is the independent
variable
Speed
THE GRAPH
Graph setup =
Formula
Dsp
a= Dt
Time
THE ACCELERATION GRAPH SETUP
Slide 7
ACCELERATION& SLOPE (QUICK VERSION)
Acceleration(Dsp/Dt)= slope on an acceleration graph (rise/run)
Acceleration Graph
+ acceleration (gas pedal)
Speed
Constant Speed
(0 acceleration)
(cruise control)
Time
- Acceleration (deceleration
(brake pedal)
No motion - stopped
Slide 8
ACCELERATION GRAPHS & SLOPE & SPEED
t
speed
• Negative (-) slope = - accel
(slowing down)
speed
• Positive (+) slope = + accel
(speeding up)
• Zero (0) slope (flat line) = 0 accel
(constant speed)
speed
t
t
Slide 9
SLOPE & TYPE OF ACCELERATION
• Steeper slopes show greater acceleration
• Straight lines = Constant acceleration
• Steady increase or decrease in speed
Accelerates slowly
t
speed
speed
Accelerates quickly
decelerates slowly
decelerates quickly
t
When is the speed = to 0 (stopped)?
Slide 10
DISCUSS THIS GRAPH
Describe which sport you think this graph
represents and why.
Golf
Skydiving
Fishing
100-meter
dash
Drag racing
Speed
Time
Slide 11
CALCULATING ACCELERATION FROM SLOPE
Rise–change in the graph on the vertical axis (Speed)
Run–change in the graph on the horizontal axis (Time)
Y2-y1
sp2-sp1
rise
Slope =
=
Acceleration=
t2-t1
X2-x1
run
Acceleration (km/h/s)
P1 (0 s, 0 km/h)
t1 sp1
P2 (20 s, 20 km/h)
t2
sp2
a=
25
sp2-sp1 20 km/h - 0 km/h
=
t2-t1
20 s– 0 s
=
20 km/h
speed (km/h)
20
P2
15
10
5
20 s
0
= 1 km/h/s
P1
0
10
20
30
40
Time (s)
50
60
70
Slide 12
ANSWERS TO SAMPLE QUESTIONS
What is the acceleration of the object from 0 – 20 s?
Acceleration(slope) =
sp2 – sp 1 (rise)
(run)
(20–0 m/s) 20 m/s
= 1 m/s/s
=
( 20 – 0 s)
20 s
What is the speed of the object from 20 – 40 s?
Acceleration(slope) =
t2 – t1
=
sp2 – sp 1 (rise) (20–20 m/s) 0 m/s
= 0 m/s/s
=
=
t2 – t1
(run) ( 40 – 20 s) 20 s
What is the speed of the object from 40 – 60 s?
Acceleration(slope) =
sp2 – sp 1 (rise)
t2 – t1
(0–20 m/s) -20 m/s
= -1 m/s/s
=
=
(run) ( 60 – 40 s) 20 s
Slide 13
ACCELERATION FORMULA, UNITS & POWER SHAPE
m/s, cm/min, km/h
final speed – initial speed
Acceleration =
final time – intial time
m/s/s, cm/min/min, km/h/s
s, min, hr
(spf – spi) Since:
a=
sp2 = final speed, sp1 = initial speed
(tf – ti)
t2 = final time, t1 = initial time
(sp2 – sp1)
a=
(t2 – t1)
Slide 14
ACCELERATION FORMULA, UNITS & POWER SHAPE
Acceleration =
final speed – start speed
final time – start time
sp2=final speed, sp1=start speed t2=final time, t1=start time
Since:
Dsp = sp2 – sp1
Dt = t2 – t1
Then:
D sp
a=
Dt
Dsp
a Dt
or x
÷
Slide 15
USING THE ACCELERATION POWER SHAPE
Dsp
a Dt
÷
A kid is sledding down a hill. When he enters the
course his speed is 10 m/s. After 2 seconds he has
reached a speed of 26 m/s. What was his
acceleration?
or x
Given
List Given Info
And Unknown:
sp1 = 10 m/s
sp2 = 26 m/s
Dt = 2 s
a= ?
Formula
Show Needed
Equations:
(sp – sp )
Dt
2
1
a = ------------
Setup
Substitute with
Units & Show Math:
26 m/s-10 m/s
a = -------------2s
Solution
Circles Answer
with Units:
a = 16 m/s
2s
a = 8 m/s/s
Slide 16
FREEFALL AND GRAVITATIONAL ACCELERATION
Freefall: Objects falling due to gravity
All objects accelerate at the same rate due to
gravity during freefall regardless of their mass
Objects
may reach terminal velocity sooner due to
air resistance
Gravitational acceleration (g) = 9.8 m/s/s on earth
Slide 17
USING THE ACCELERATION POWER SHAPE
Dsp
a Dt
÷
A woman jumps from a plane. She opens her
parachute five seconds later. How fast was she
going when she opened her shoot (disregard air
resistance)?
or x
Given
List Given Info
And Unknown:
Dsp = ??
Dt = 5 s
a= g=9.8 m/s/s
Formula
Show Needed
Equations:
Dsp = a · Dt
Setup
Substitute with
Units & Show Math:
Dsp =9.8 m/s/s · 5 s
Solution
Circles Answer
with Units:
Dsp = 49.2 m/s
zoom zoom
ACCELERATION
Slide 2
ACCELERATION TERMS
Acceleration (a)– the rate of change of velocity
(can be +, -, or centripetal)
Deceleration– only negative acceleration
(slowing down)
Centripetal Acceleration– acceleration that
occurs when changing direction (turning)
Freefall– objects falling due to gravity
Force is what you feel when you accelerate
Slide 3
3 WAYS TO ACCELERATE
Since acceleration is a change in velocity and
velocity has 2 parts
We can accelerate by
Changes
1.
2.
in speed
Speed up (+ acceleration)
Slow down (- acceleration)
Changing
3.
Direction
Turning
Changing
both speed and direction
Slide 4
YOUR SPEEDOMETER – THE KEY TO ACCEL
We don’t see
acceleration of an
object well with our eyes
But if we look at a
speedometer we can
see speed change.
Acceleration is a picture
of what your
speedometer is doing
Slide 5
SLOW ACCELERATION
FAST(ER) ACCELERATION
ACCELERATION IS A PIC OF YOUR SPEEDO
Slide 6
THE VARIABLES
Speed ( or velocity)is the
dependent variable
Time is the independent
variable
Speed
THE GRAPH
Graph setup =
Formula
Dsp
a= Dt
Time
THE ACCELERATION GRAPH SETUP
Slide 7
ACCELERATION& SLOPE (QUICK VERSION)
Acceleration(Dsp/Dt)= slope on an acceleration graph (rise/run)
Acceleration Graph
+ acceleration (gas pedal)
Speed
Constant Speed
(0 acceleration)
(cruise control)
Time
- Acceleration (deceleration
(brake pedal)
No motion - stopped
Slide 8
ACCELERATION GRAPHS & SLOPE & SPEED
t
speed
• Negative (-) slope = - accel
(slowing down)
speed
• Positive (+) slope = + accel
(speeding up)
• Zero (0) slope (flat line) = 0 accel
(constant speed)
speed
t
t
Slide 9
SLOPE & TYPE OF ACCELERATION
• Steeper slopes show greater acceleration
• Straight lines = Constant acceleration
• Steady increase or decrease in speed
Accelerates slowly
t
speed
speed
Accelerates quickly
decelerates slowly
decelerates quickly
t
When is the speed = to 0 (stopped)?
Slide 10
DISCUSS THIS GRAPH
Describe which sport you think this graph
represents and why.
Golf
Skydiving
Fishing
100-meter
dash
Drag racing
Speed
Time
Slide 11
CALCULATING ACCELERATION FROM SLOPE
Rise–change in the graph on the vertical axis (Speed)
Run–change in the graph on the horizontal axis (Time)
Y2-y1
sp2-sp1
rise
Slope =
=
Acceleration=
t2-t1
X2-x1
run
Acceleration (km/h/s)
P1 (0 s, 0 km/h)
t1 sp1
P2 (20 s, 20 km/h)
t2
sp2
a=
25
sp2-sp1 20 km/h - 0 km/h
=
t2-t1
20 s– 0 s
=
20 km/h
speed (km/h)
20
P2
15
10
5
20 s
0
= 1 km/h/s
P1
0
10
20
30
40
Time (s)
50
60
70
Slide 12
ANSWERS TO SAMPLE QUESTIONS
What is the acceleration of the object from 0 – 20 s?
Acceleration(slope) =
sp2 – sp 1 (rise)
(run)
(20–0 m/s) 20 m/s
= 1 m/s/s
=
( 20 – 0 s)
20 s
What is the speed of the object from 20 – 40 s?
Acceleration(slope) =
t2 – t1
=
sp2 – sp 1 (rise) (20–20 m/s) 0 m/s
= 0 m/s/s
=
=
t2 – t1
(run) ( 40 – 20 s) 20 s
What is the speed of the object from 40 – 60 s?
Acceleration(slope) =
sp2 – sp 1 (rise)
t2 – t1
(0–20 m/s) -20 m/s
= -1 m/s/s
=
=
(run) ( 60 – 40 s) 20 s
Slide 13
ACCELERATION FORMULA, UNITS & POWER SHAPE
m/s, cm/min, km/h
final speed – initial speed
Acceleration =
final time – intial time
m/s/s, cm/min/min, km/h/s
s, min, hr
(spf – spi) Since:
a=
sp2 = final speed, sp1 = initial speed
(tf – ti)
t2 = final time, t1 = initial time
(sp2 – sp1)
a=
(t2 – t1)
Slide 14
ACCELERATION FORMULA, UNITS & POWER SHAPE
Acceleration =
final speed – start speed
final time – start time
sp2=final speed, sp1=start speed t2=final time, t1=start time
Since:
Dsp = sp2 – sp1
Dt = t2 – t1
Then:
D sp
a=
Dt
Dsp
a Dt
or x
÷
Slide 15
USING THE ACCELERATION POWER SHAPE
Dsp
a Dt
÷
A kid is sledding down a hill. When he enters the
course his speed is 10 m/s. After 2 seconds he has
reached a speed of 26 m/s. What was his
acceleration?
or x
Given
List Given Info
And Unknown:
sp1 = 10 m/s
sp2 = 26 m/s
Dt = 2 s
a= ?
Formula
Show Needed
Equations:
(sp – sp )
Dt
2
1
a = ------------
Setup
Substitute with
Units & Show Math:
26 m/s-10 m/s
a = -------------2s
Solution
Circles Answer
with Units:
a = 16 m/s
2s
a = 8 m/s/s
Slide 16
FREEFALL AND GRAVITATIONAL ACCELERATION
Freefall: Objects falling due to gravity
All objects accelerate at the same rate due to
gravity during freefall regardless of their mass
Objects
may reach terminal velocity sooner due to
air resistance
Gravitational acceleration (g) = 9.8 m/s/s on earth
Slide 17
USING THE ACCELERATION POWER SHAPE
Dsp
a Dt
÷
A woman jumps from a plane. She opens her
parachute five seconds later. How fast was she
going when she opened her shoot (disregard air
resistance)?
or x
Given
List Given Info
And Unknown:
Dsp = ??
Dt = 5 s
a= g=9.8 m/s/s
Formula
Show Needed
Equations:
Dsp = a · Dt
Setup
Substitute with
Units & Show Math:
Dsp =9.8 m/s/s · 5 s
Solution
Circles Answer
with Units:
Dsp = 49.2 m/s