Chapter 2: Describing motion
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Transcript of Chapter 2: Describing motion
Kinematics : a branch of physics that studies motion
Describing Motion
Photo taken by Rasha Alkhateeb Jubilee School
Speed vs. Velocity* Speed is a scalar (how fast
something is moving regardless of its direction). Ex: v = 20 mps
* Speed is the magnitude of velocity.* Velocity is a combination of speed
and direction. Ex: v = 20 mps, at 15 south of west
* The symbol for speed is v.* The symbol for velocity is type
written in bold: (v) or hand written with an arrow: v
Mass vs. Weight
your mass would be the same, but the magnitude of your weight would be less.
Mass• Scalar (no direction)• Measures the amount of matter in an objectWeight• Vector (points toward center of Earth)• Force of gravity on an object& On the
moon!!!
Some Physics Quantities Scalars --------------------------- Vectors • Distance ----------------------- Displacement• Speed ---------------------------- Velocity• Mass ------------------------------- Weight•Time ----------------------------------------------- • Energy --------------------------------------------• ----------------------------------------------- Force (magnitude & direction)
Some UnitsQuantity .………………... Unit (symbol)
Displacement & Distance ….… meter (m)
Time …………………………. second (s)
Velocity & Speed ……………….(m/s)
Mass ……………………… kilogram (kg)
Force ………………………. Newton (N)
Some “SI Prefixes”
nano n 10-9
micro µ 10-6
milli m 10-3
centi c 10-2
deci d 10-1
deka da 101
hecto h 102
kilo k 103
mega M 106
giga G 109
Little Guys Big Guys
Another problem: A car travels 10,000 meters in 6 minutes, what is the car’s speed?
0.29 seconds
The answer
1) a 2) b 3) a
3.3 m/s
“Distance versus Time” Graphs
Graphing
A … Starts at home (origin) and goes forward slowlyB … Not moving (position remains constant as time progresses)C … Turns around and goes in the other direction quickly, going back home.
1 – D Motion
x
t
AB
C
SPEED IS THE SLOPE OF THE DISTANCE VERSUS TIME
GRAPH
DISTANCE VS. TIME GRAPHS
O A & D E
A B & E F C D
B C
a = zerov = zero
v: constantd: increases uniformly
a = zero
d: increases nonu-niformly
v: increases uniformly
a: constant
d: constant
Graphing Animation Link
This website will allow you to set the initial velocity and acceleration of a car. http://www.walter-fendt.de/ph14e/acceleration.htm
Car Animation
Thank you for being with us. Have a nice day Amal Sweis