Displacement
-
Upload
chaiporn-pattanajak -
Category
Documents
-
view
181 -
download
2
Transcript of Displacement
It is a change in the position of an object with respect to time.
Section I :POSITION, DISTANCE & DISPLACEMENT
Straight
Let’s look the picture
Introduce•การเคลื่��อนที่��ค�อ การเปลื่��ยนตำ�าแหน�งหร�อการกระจั�ดของวั�ตำถุ�ตำามเวัลื่าที่��เปลื่��ยนไป
Let’s look the picture
Old position
Let’s look the picture
Old positionNew position
New position
A
B
Can you tell me about rockets A and rockets B!
Old position
Let’s look the picture
Old positionNew position
New position
A
BWe can say, rocket A moving and B No !
Moving object is identified by its change of position from a certain point of reference
ตำ�าแหน�งอ างอ!ง
ตำ��แหน่�งอ้�งอ้�งเริ่��มตำน่ สิ้��น่สิ้�ด
•ก�ริ่กริ่ะจั�ด (Displacement) เป"นปร!มาณ vector จัะตำ องม�ขนาด(ระยะที่าง) แลื่ะที่!ศที่าง
•ริ่ะยะท�ง (Distance) เป"นปร!มาณ Scalar ม�เฉพ�ะขน่�ด
Start
Finish
A
B
• Set up a coordinate system –Right is usually positive, left is usually
negative.
– Distance = total length of travel
– Displacement = change in position = final position – initial position or ∆x = xf - xi
• Displacement can be positive, negative, or zero
• ริ่ะยะท�งจั�กบ้�น่เพ��อ้น่ ถึ"งริ่�น่ค้�กลั�บ้ไปท��บ้�น่ขอ้งตำน่เอ้งเป'น่เท��ใด
• ก�ริ่กริ่ะจั�ดเป'น่เท��ใด• ที่�าอย�างไรจัะที่�าให การกระจั�ดเป"น
ศ&นย'
2 km
4 km
7-11
In this section you are able to :
1. Making a graph of displacement vs time
2. Finding the equation of speed
3. Identifying the application of constant straight motion in daily life
Section II :
• Average Speed and Velocity
Speed is scalar quantity.(Blue curve)
time
cedisv
tan
Unit : m/s
Velocity is vector quantity. (Green line)
time
ntdisplacemev
Unit : m/st
x
tt
xxv
if
if
t
x
tt
xxv
if
if
ix
fx
Base on component that contents of quantities, quantities can be derived in two kind :
1.Vector (velocity) 2.Scalar (speed)
VelocityFor example1.If some one walking 5
km/hour toward east :a. his speed is 5 km/hourb. his velocity is 5 km/hour to east.
Graphical Interpretation of Average Velocity
Slope of a line connecting two points on an displacement vs. time plot is equal to the average velocity during that time interval
The relationship among d, t, and v
t
dv
v
dt
tvd .
d
v t
Calculating the velocityAverage speed is the total
traveled distance divided by the time needed to travel that distance.
t
dv
v = average speedd = total distancet = time total
•We can use the slopeslope of a distance – time graphs to find the speed of an object.
•To do this the graph line must be straight.straight.
t
xSlope
Copy
Slope = velocity
Handout
Calculate the slopeslope for each Car
•The average speed of Car A =•The average speed of Car B =•The average speed of Car C =
Time (h) Speedometer Car A (kmh-1)
0 50
0.5 50
1.0 50
1.5 50
2.0 50
2.5 50
3.0 50
3.5 50
4.0 50
Copy
Identify pleace!
Identify pleace!