# Chapter One Motion

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14 Νοε 2013 (πριν από 4 χρόνια και 7 μήνες)

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Chapter One

Motion

Mrs. Swanson

I. Describing Motion

A. Describing Motion
-

An object is in motion if its distance
from another object is changing.

B. Reference Point

A place or object used for
comparison. An object is in motion
if…it changes position relative to a
reference point. (
ie
. Tree, sign,
building)

C. Relative Motion

Depends on the reference point you
choose

D. Measuring Distance

SI Units

International Units of
Measure

A. Length
-

Meter, Centimeter,
Millimeter.

B. Converting Units Math Skills
-

1,000mm

or
100 cm

1m

1m

Measuring Distance

Meter

= 50 m

1 mm

international unit for measuring
distance.

Speed and
Velocity

Measuring motion

E. CALCULATING SPEED
-

The distance an object travels in
a certain amount of time, you
can calculate the speed of the
object.

Units for speed

Depends…

but will always be a distance unit /
a time unit

Examples:

mi./h

km/h

cm/s

m/s

Cars:

Jets:

Snails:

Falling objects:

Calculating speed

If I travel 100 kilometer in one hour
then I have a speed of…

100 km/h

If I travel 1 meter in 1 second then
I have a speed of….

1 m/s

1.
The speed Equation

2.
S
= d/t

2. Average speed

Speed is usually NOT CONSTANT

Examples:

Cars stop and go regularly

Runners go slower uphill than
downhill

Average speed

=

total distance
traveled/total
time it took.

Calculating Average Speed

It took me 1 hour to go 40 km on the
highway. Then it took me 2 more hours to
go 20 km using the streets.

Total Distance:

40 km + 20 km = 60 km

Total Time:

1 h + 2 h = 3 hr

Average Speed:

3. Instantaneous Speed

Rate at which an object is moving
at a given instant in time

Question

I ran 1000 m in 3 minutes. Then
ran another 1000 m uphill in 7
minutes. What is my average
speed?

A) 100 m/min

B) 2000 m/min

C) 10 m/min

D) 200 m/min

E) 20 m/min

Total Dist. =
1000 m + 1000 m =
2000 m

Total Time =
3 min + 7 min =
10 min

Average
speed =
total
distance/total
time
=

2000m/10 min
=

200 m/min

4.
DescribingVelocity

Velocity

the SPEED and
DIRECTION of an object.

“Speed in a given direction”

Example:

Airplane moving
North

at 500 mph

Missile moving
towards you
at
200m/s

Question

What is the difference
between speed and velocity?

Speed is just distance/time.
Velocity includes direction as
well.

F. Graphing Motion

Distance vs. Time on a line graph

1. y axis vertical

2. x axis horizontal

3. steepness of the line

Slope=
Rise

Run

http://www.phschool.com/webcodes10/index.cfm?fu
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ix=3011

II. Acceleration

A. Definition
-

The rate at which
velocity changes. “The process of
speeding up”

1. Increasing Speed= The object
accelerates

2. Decreasing Speed= Negative
Acceleration

3. Changing Direction= Object that is
traveling at a constant speed can
still be accelerating.

B. Calculating Acceleration

Change in speed over time

Acceleration =
Final speed
-

Initial
Speed

Time

C. Graphing Acceleration

1. Speed versus time
-

Slope=
Rise

Run

2. Distance versus time graph