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Preliminary Physics Topic 3

MOVING ABOUT

What is this topic about?

To keep it as simple as possible, (K.I.S.S.) this topic involves the study of: 1. SPEED and VELOCITY

2. FORCE and ACCELERATION

3. WORK and KINETIC ENERGY

4. MOMENTUM and IMPULSE

5. SAFETY DEVICES in VEHICLES

...all in the context of moving vehicles.

but first, let’s revise...

WHAT IS SPEED?

WHAT IS ENERGY?

“Speed” refers to how fast you are going.

You already know that mathematically:

Energy is what causes changes....

change in temperature (Heat energy)

change in speed (Kinetic energy)

change in height

(gravitational Potential energy)

change in chemical structure

(chemical P.E.)

...and so on.

SPEED = distance travelled

time taken

In this topic, you will extend your understanding

of speed to include VELOCITY, which is just a

special case of speed.

In this topic the most important energy form you

will study is the one associated with moving

vehicles...

WHAT IS FORCE?

A FORCE is a PUSH or a PULL.

KINETIC ENERGY

Some forces, like gravity and electric/magnetic

fields, can exert forces without actually

touching things. In this topic you will deal

mainly with CONTACT FORCES, which push or

pull objects by direct contact.

WHAT MAKES A CAR GO?

Overview

of Topic:

ENGINE provides ENERGY

(from chemical energy

in petrol)

Tyres PUSH on road...

FORCE acts...

FORCE causes

ACCELERATION

In the context of moving vehicles, the most

important force is FRICTION. Friction allows a

car’s tyres to grip the road to get moving, and

for the brakes to stop it again. Without friction

the car couldn’t get going, and couldn’t stop if it

did!

Preliminary Physics Topic 3 “Moving About”

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FORCE acts over

a distance...

“WORK” done

KINETIC

ENERGY

changes

VELOCITY

changes

1

MOMENTUM

changes

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CONCEPT DIAGRAM (“Mind Map”) OF TOPIC

Some students find that memorising the OUTLINE of a topic helps them learn and remember the concepts and important facts. As you proceed through the topic, come back to this page regularly to see how each bit fits the whole. At the end of the notes you will find a blank version of this “Mind Map” to practise on.

Average &

Instantaneous

Speed

Motion

Graphs

Forces

Vectors & Scalars.

Speed & Velocity

Adding

Vectors

Acceleration

Mass

&

Weight

Measuring

Motion

Speed

&

Velocity

Force

&

Acceleration

Newton’s

2nd Law

Centripetal

Force

MOVING

ABOUT

Work

&

Kinetic Energy

Energy

Transformations

Safety Devices

in

Vehicles

Momentum

&

Impulse

Equivalence of

Work & Energy

Law of

Conservation

of Energy

Momentum

Physics of

Safety

Devices

Inertia

&

Newton’s

1st Law

Preliminary Physics Topic 3 “Moving About”

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Newton’s

3rd Law

Impulse

of a Force

Conservation

of Momentum

in Collisions

2

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1. SPEED & VELOCITY

Average Speed for a Journey

If you travelled by car a distance of 300 km in exactly 4 hours, then your “average speed” was: average speed

=

distance travelled

time taken

=

300

4

=

75 km/hr (km.hr-1)

However, this does not mean that you actually travelled at a speed of 75 km/hr the whole way. You probably went faster at times, slower at other times,

and may have stopped for a rest at some point.

Distance-Time Graphs

Speed-Time Graphs

Perhaps your journey was similar to this graph.

The same journey could also be represented by

a different graph, showing the SPEED at

different times:

Start at the bottom-left of the graph and consider

each section A, B, C and D.

100

These graphs

represent the

same journey

A

0

1

2

3

TIME (hours)

4

1

Stopped.

Speed scale

reads zero.

2

TIME (hr)

3

4

This graph is very unrealistic in one way. It

shows the speed changing INSTANTLY from

(say) 100 km/hr to zero (stopped), without any

time to slow down. It also shows the car

travelling at exactly 100 km/hr for an hour at a

time... very unlikely with hills, curves, traffic etc.

This raises the idea of INSTANTANEOUS

SPEED: the speed at a particular instant of time.

The speedometer in your car gives you a

moment-by-moment reading of your current

speed... this is your instantaneous speed.

Changes of speed (ACCELERATION) will be

dealt with in the next section. For now we’re

Keeping It Simple!

On the graph, the GRADIENT at any given point

is equal to INSTANTANEOUS SPEED.

SPEED-TIME GRAPHS

show the SPEED of a moving object

at each TIME.

DISTANCE-TIME GRAPHS

show the DISTANCE (from the starting point)

at each TIME.

The GRADIENT at any point equals

INSTANTANEOUS SPEED.

The speed at any time can be read from

the vertical scale of the graph.

A horizontal section means that

the object was moving at constant speed.

A horizontal section means that

the object was not moving

Preliminary Physics Topic 3 “Moving About”

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B

0

So although the average speed for the entire

journey was 75km/hr, in fact you never actually

moved at that speed.

“Flat” parts

DO NOT

mean

stopped,

but mean

constant

speed

C

20

gradient = zero

i.e. stopped

SPEED (km/hr)

40

60

80

300

C

B

D

A

0

Graph section A

Travelled 100 km

in 1.0 hour:

Speed =100 km/hr

You must not confuse the 2 types of graph and

how to interpret them.

D

50

Graph section B

Zero distance

moved in 0.5 hr:

Speed= zero.

gradient = distance

time

= speed

0

Graph section C

Travelled 50 km

in 1.0 hr:

Speed=50 km/hr

Study this graph carefully and compared it with

the other...

Distance-T

Time Graph

DISTANCE TRAVELLED (km)

100

150

200

250

Graph section D

Travelled 150km

in 1.5 hr:

Speed = 100 km/hr

3

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Scalars & Vectors

A Scalar quantity is something that has a size

(magnitude) but no particular direction.

A Vector quantity has both size (magnitude) AND

DIRECTION.

BUT, consider the “NET journey”: at the end of

the journey you end up 30 km EAST of the

starting point. So, your final displacement is “30

km east”.

So far we have dealt with only distances &

speeds... these are Scalar quantities, since they

do not have any special direction associated.

The VECTOR journey was:

• travelled 30 km east displacement in 1.5 hours.

• average velocity = 30/1.5 = 20 km/hr east.

Now you must learn the vector equivalents:

“Displacement” = distance in a given direction,

and

“Velocity” = speed in a given direction.

Notice that both displacement and velocity have

a direction (“east”) specified....

they are

VECTORS!

To make better sense (mathematically) of the

journey, the directions east & west could have

(+) or ( - ) signs attached. Let east be (+) and

west be ( - ).

Then the total

Average = Displacement

journey

Velocity

time

displacement was

Consider this journey:

drove 60 km EAST in 1 hour

START

then

drove 30 km WEST

in 0.5 hour.

(+60) + (-30) = +30 km.

Vav = S

t

As a SCALAR journey:

• travelled a total 90 km distance in 1.5 hours,

• average speed = 90/1.5 = 60 km/hr

Note: The symbol “S” is used for Displacement

MORE GRAPHS... Displacement - Time

...and the corresponding Velocity - Time Graph:

100

Refer to the previous Distance-Time graph.

What if the 300km journey had been 150 km north

(sections A, B, C) then 150 km south (section D)?

Back at starting point.

(Displacement = 0 )

1

2

TIME (hours)

3

4

In vector terms; displacement north is positive (+)

displacement south is negative ( - )

In section D:

displacement = -150 km (south)

C

TIME (hrs)

B

1

Zero velocity:

means stopped

2

3

4

Negative value:

south-b

bound

velocity

D

The velocity values for each part of this graph

are equal to the gradients of the corresponding

parts of the Displacement - Time Graph.

Note: Since the journey ends back

at the starting point,

total displacement = zero

and average velocity = zero

for the whole trip.

velocity = displacement

time

= -150 /1.5

= -100 km/hr (i.e. 100km/hr southward)

Preliminary Physics Topic 3 “Moving About”

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0

-1

100

0

south

-5

50

po

sit

ive

Gr

ad

ien

t

D

ve

ati

neg

Displacement NORTH (km)

0

50

100

nt

die

Gra

B

Velocity (km/hr)

150

Downsloping

line means

travelling

SOUTH

C

A

north

50

The Displacement - Time Graph would be:

Positive values mean

north-b

bound velocity

A

However, this simply points out how little

information the “average” gives you.

The instant-by-instant Physics of the

journey is in the graph details.

4

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Measuring Motion

Prac Work:

You will probably experience one or more of these commonly used ways to measure motion in the laboratory.

You might do some measurements as

suggested by this diagram

Time to travel from A to B measured by stopwatch

Distance between landmarks measured with sports tape

Landmark

A

Tape Measure & Stopwatch

The simplest method of all: measure the distance

or displacement involved, and the time taken.

Then use

speed (velocity) = distance (displacement)

time

Typical Results

Distance

Time

Velocity

(m)

(s)

(ms-1)

Car

Bicycle

87

87

6.2

22.4

Landmark B

The “Ticker-Timer”

Every time the hammer hits the

moving strip of paper

it leaves a dot.

The string of dots can be

analysed to study the

motion of the trolley.

Moving lab. trolley

drags a strip of

paper behind it

“Ticker-ttimer” device has a small hammer

which vibrates up and down every 0.02 sec.

14.0

3.9

However, this can only give you the AVERAGE

speed or velocity. In Physics we often need to

consider INSTANTANEOUS velocity.

Although this method is very out-dated, it is

still commonly used as a way for

students to learn how to measure

instantaneous velocity.

A moving object drags a paper strip on

which dots get printed (usually every 0.02

second) as it goes. The gap between dots is

a record of displacement and time. This

allows you to calculate the velocity over

every 0.02 s. It’s still an average, but over

such small time intervals it approximates

the instantaneous velocity.

Electronic or Computer Timing

You may use devices that use either “Light

Gates” or “SONAR” to record displacements

and times for you.

Once again, any velocities calculated are

averages, but the time intervals are so short

(e.g. as small as 0.001 s) that the velocity

calculated is essentially instantaneous.

Moving trolley equipped with a

sonar reflector.

(An aluminium pie dish will do)

Sonar “transponder” gives out

pulses of ultra-s

sound and picks

up any returning echoes

To computer for

analysis

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Worksheet 1

Speed & Velocity

Fill in the blank spaces.

Student Name...........................................

On a displacement-time graph, movement south

would

result

in

the

graph

sloping

m)................................... to the right and having a negative n)............................................

The average speed of a moving object is equal

to the a)............................ travelled, divided by

b)....................... taken. On a Distance-Time

graph, the c)........................ of the graph is equal

to speed. A horizontal graph means

d)................................. ...............................

The

vector

equivalent

of

speed

is

o).................................... The average velocity is equal to p)............................... divided by

q)....................... Instantaneous velocity refers to

r)..................................................................

On a Speed-Time graph, constant speed is

shown by e).......................................... on the graph. This does NOT mean stopped, unless the

graph section is lined up with f).............................

Laboratory methods for measuring motion

include using a tape measure and stopwatch.

This allows calculation of s)....................

............................ only. “Ticker-timers” record both t)............................... and .......................... on a paper tape. Average velocity can be calculated

for short time intervals which are approximately

equal to u)............................................ velocity. • Electronic or Computer-based devices often

use v)........................ or ......................................... to gather displacement, time and velocity data at

very short time intervals.

Speed and distance are both g).............................. quantities, because the direction doesn’t matter.

Often in Physics we deal with h)............................ quantities, which have both i)............................... and .......................................

The vector equivalent of distance is called

j)................................., and refers to distance in a particular k).............................. For example, if

displacement was being measured in the north

direction, then a distance southward would be

considered as l).............................. displacement.

Worksheet 2

Motion Graphs

Practice Problems

Student Name...........................................

A car travelled 200 km north in 3.0 hours, then

stopped for 1.0 hr, and finally travelled south 100

km in 1.0 hr.

1. What was the total distance travelled?

7. Use your graph to find:

i) average velocity for the first 3 hours.

ii) velocity during the 4th hour.

2. What was the total displacement?

iii) velocity during the last hour.

3. What was the total time for the whole journey?

4. Calculate the average

speed for the whole journey.

North

100

8. Construct a Velocity- Time Graph for this trip.

Time (hr)

0

Velocity (km/hr)

1

2

3

4

5

-1

100

South

-5

50

Displacement

6. Construct a

Displacement - Time

Graph for this trip.

50

5. Calculate the average velocity for the whole

journey.

TIME

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Worksheet 3

Practice Problems

Motion Graphs & Calculations

800

1. An aircraft took

off from town P and

flew due north to

town Q where it

stopped to re-fuel. It

then flew due south

to town R.

UNITS OF MEASUREMENT

So far all examples have used the familiar

km/hr for speed or velocity. The correct S.I.

units are metres per second (ms-1). You need

to be able to work in both, and convert from

one to the other.....

here’s how:

1 km/hr = 1,000 metres/hr

= 1,000m/(60x60) seconds

= 1,000/3,600 m/s

= 1/3.6

So, to convert km/hr

ms-1 divide by 3.6

to convert ms-1

km/hr multiply by 3.6

200

400

600

Displacement north (km)

Q

P

Time

(hr)

1

2

3

4

5

-4

400 -2

200

The trip is

summarised by the

graph.

Student Name...........................................

6

R

a) How far is it from towns P to Q?

2. A car is travelling at 100 km/hr.

a) What is this in ms-1?

b) How long did the flight P to Q take?

c) Calculate the average velocity for the flight

from P to Q (include direction)

b) The driver has a “micro-sleep” for 5.00 s. How far

will the car travel in this time?

c) At this velocity, how long does it take (in seconds)

to travel 1.00km (1,000m)?

d) What is the value of the gradient of the

graph from t=3 hr, to t=6 hr.?

3.

For this question consider north as (+), south as ( - ).

e) What part of the journey does this

represent?

A truck is travelling at a velocity of +20.5 ms-1 as it

passes a car travelling at -24.5 ms-1.

f) Where is town R located compared to town P?

a) What are these velocities in km/hr? (including

directions?)

g) What was the aircraft’s position and velocity

(including direction) at t=5 hr?

b) What is the displacement (in m) of each vehicle in

30.0 s?

h) What was the:

i) total distance

c) How long would it take each vehicle to travel

100 m?

ii) average speed

iii) total displacement

4. Where does this aircraft end up in relation to its

starting point?

iv) average velocity

(for the entire 6 hr journey)

Next, flew east at 105 ms-1 for 50.0 minutes.

100

200

Velocity (km/hr)

North

Next, flew west for 3.25 hours at 325 km/hr.

Time (hr)

0

i) Construct a

Velocity- Time

Graph for

the flight.

300

400

Flight details:

First flew west for 2.50 hr at 460 km/hr.

2

3

4

5

6

Finally flew east for 5.50 hours at velocity 125 ms-1.

-3

300

South

-1

100

1

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2. FORCE & ACCELERATION

Graphs of Accelerating Vehicles

Change of Velocity = Acceleration

You may have done laboratory work to study the

motion of an accelerating trolley. If you used a

“Ticker-timer”, the paper tape records would

look something like this:

Any change in velocity is an acceleration.

Mathematically,

acceleration = velocity change = final vel. - initial velocity time taken

time taken

Tape of trolley accelerating... dots get further apart

v = final velocity

u = initial velocity

t = time involved

Trolley decelerating (negative acceleration)... dots get closer

Units: if velocities are in ms-1, and time in

seconds, then acceleration is measured in

metres/sec/sec (ms-2).

The graphs that result from acceleration are as

follows:

Explanation: Imagine a car that accelerates at 1 ms-2:

1 sec. later

v = 1 ms-1

1 sec.later

v=2 ms-1

Remember,

Gradient

equals

Velocity

1sec.later

v=3ms-1

Displacement

Every second, its velocity increases by 1 ms-1.

Therefore, the rate at which velocity is changing

is 1 ms-1 per second, or simply 1 ms-2.

Acceleration is a vector, so direction counts.

+

ACCELERATION

VECTOR

VELOCITY

VECTOR

DISPLACEMENT-T

TIME GRAPH

Gradients decreasing

(curve flattens out)

THIS CAR IS SLOWING

DOWN... DECELERATING

ing

rat

ele

c

De

Gradient constant

(straight line)

Gradients increasing

(curve gets steeper)

Time

“Deceleration” (or negative acceleration) simply

means that the direction of acceleration is

opposite to the current motion... the vehicle will

slow down rather than speed up.

VELOCITY-T

TIME GRAPH

Constant

Velocity

A motorcycle travelling at 10.0 ms-1, accelerated

for 5.00s to a final velocity of 30.0 ms-1. What was

its acceleration rate?

Velocity

increasing

Solution: a = v - u = 30.0-10.0/5.00 = 20.0/5.00

t

= 4.00 ms-2.

A common error is to

think that this means the

object is moving

backwards. Wrong! It is

moving forward, but

slowing down.

g

in

at

ler

ce

De

Velocity

Example Problem 1

Ac

ce

ler

at

in

g

Start

v =0

Co

Ve nsta

loc nt

ity

a=v-u

t

Δ (Greek letter “delta”) refers

to a change in a quantity

Ac

ce

le

ra

tin

g

a = Δv

Δt

Tape of trolley moving at constant velocity (for comparison)

Velocity

decreasing

Velocity = 0

∴ Stopped!

Example Problem 2

A car moving at 25.0 ms-1 applied its brakes

producing an acceleration of -1.50 ms-2

(i.e. deceleration) lasting for 12.0 s.

What was its final velocity?

Solution: a = v - u,

t

Time

Gradient positive

so v = u + at

= 25.0 + (-1.50) x 12.0

= 25.0 - 18.0

= 7.00 ms-1.

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Gradient negative

On a Velocity-T

Time Graph

Gradient = Acceleration

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Force Causes Acceleration

PRESSING ON THE ACCELERATOR...

A simple definition of “Force” is a push or a pull.

However, in the context of moving vehicles,

Weight

Vertical forces are

balanced, and cancel

Force is what causes

velocity to change.

Thrust Force

Increased

Note that a change of velocity could mean:

• speeding up

• slowing down

• changing direction (velocity is a vector)

Friction &

Air Resistance

small forces

Horizontal forces

UNBALANCED

Reaction

Force

To actually result in a change of velocity, the

force must be

External

and

For example, if you were

inside a moving car and

kicked the dashboard,

this force would have NO

EFFECT on the car’s

motion...

This is an “Internal Force”

and cannot cause

acceleration.

TURNING THE STEERING WHEEL...

Unbalanced (Net) Force

Vertical forces are

balanced, and cancel

Forward & Back

Forces are balanced

and cancel

WEIGHT FORCE

Car pushes on Earth

(Thrust Force from

Engine is equal to

Friction forces)

Sideways

Forces become

UNBALANCED

(These would

be equal if

wheel not

turned)

Thrust

from

Engine

Friction

and Air

Resistance

This car will

SPEED UP

REACTION FORCE

Earth pushes back

This car will turn a corner

at constant speed

(but this is a changed velocity

since the direction changed)

BALANCED & UNBALANCED FORCES

GOING UP A HILL

(without increasing engine thrust)

The car above has a number of forces acting on

it, but they are BALANCED... those acting in the

same line are equal and opposite,

and cancel each other out.

This car will not alter its velocity or direction; it

will not accelerate. It is either travelling at a

constant velocity, or it is stationary.

EXAMPLES OF

BALANCED

UNBALANCED

FORCE

FORCES

SITUATION

Engine Thrust

still the same

Part of the

Weight Force acts

downhill to cancel

some of the thrust

Reaction Force is not

vertical, and no

longer cancels the

weight completely...

UNBALANCED FORCE

This bike will SLOW DOWN.

(Going down a hill, it will speed up)

PASSING OVER AN ICY PATCH ON THE ROAD

Opposite Forces are

BALANCED and cancel

Friction

still the

same

Weight (still vertical)

Weight

PRESSING ON THE BRAKES...

Virtually no

Thrust Force

because tyres

can’t grip on ice

This car will continue

in a straight line, at a

constant velocity...

whether the driver

wants to or not...

Vertical forces are

balanced, and cancel

Virtually

no Friction

on Ice

Weight

Thrust Force

decreases as

Friction

Increases as

Brakes are

applied

accelerator is

released

Reaction Force

cancels Weight

Car is out of control;

Can’t stop...

Can’t turn...

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*05.elements*

*056*

*056km*

*06.cells*

*07.life*

*08.lifesystems*

*09.astronomy*

*1*

*1.0*

*1.00*

*1.05*

*1.08*

*1.1*

*1.10*

*1.15*

*1.19*

*1.2*

*1.25*

*1.3*

*1.32*

*1.33*

*1.4*

*1.40*

*1.43*

*1.5*

*1.50*

*1.59*

*1.7*

*1.70*

*1.73*

*1.75*

*1.8*

*1.80*

*1.82*

*1.83*

*1.9*

*1.93*

*1/3.6*

*10*

*10.0*

*10.5*

*10.6*

*10.earth*

*100*

*100/150*

*100/20.5*

*100/200*

*100/24.5*

*100/3.6*

*100/5*

*1002*

*100kg*

*100km*

*100km/hr*

*100m*

*100n*

*100v*

*102*

*105*

*105j*

*105x*

*1067*

*10ms*

*10n*

*10s*

*11*

*11.ecosystems*

*117o*

*1190n*

*12*

*12.0*

*12.5*

*12.waves*

*120*

*1200n*

*120kg*

*120n*

*120x5.25*

*1240ns*

*125*

*125/8.75*

*1250*

*125x*

*13*

*13.3*

*13.9*

*13.motion*

*1300*

*133*

*138063711*

*139m*

*13s*

*14*

*14.0*

*14.1*

*14.8*

*14.9*

*14.electricity*

*140*

*140/3.6*

*140km/hr*

*143o*

*144o*

*146o*

*14ms*

*15*

*15.0*

*15.3*

*15.atoms*

*150*

*1500*

*1502*

*150km*

*150ms*

*150n*

*150x60*

*15kg*

*16*

*16.reactions*

*160*

*160kj*

*1642*

*166ms*

*17*

*17.dna*

*18*

*18.0*

*18.evolution*

*180/3.00*

*180kg*

*180km*

*180x35.0*

*19*

*19.0*

*19.health*

*1kg*

*1ms*

*1n*

*1sec.later*

*1st*

*2*

*2.0*

*2.00*

*2.03*

*2.15*

*2.20*

*2.23*

*2.25*

*2.3*

*2.4*

*2.48*

*2.5*

*2.50*

*2.65*

*2.74*

*2.90*

*20*

*20.0*

*20.5*

*20.universe*

*20/200*

*200*

*200/150*

*200/3*

*200/900*

*2000*

*2002*

*2005*

*2009*

*200g*

*200kg*

*200km*

*200ms*

*200n*

*200x75.0*

*201*

*201ms*

*202*

*20km/hr*

*20ms*

*20n*

*20o*

*20x3.6*

*20x4.0*

*21*

*21.earthscience*

*210m*

*218.18*

*22*

*22.0*

*22.2*

*22.4*

*22.5*

*22.resources*

*224*

*225*

*23*

*23.0*

*24*

*24.5*

*240/32.5*

*2444*

*248*

*25*

*25.0*

*25.02*

*25/40*

*250*

*250/3.00*

*250/500*

*250g*

*250kg*

*250km*

*250km/hr*

*250m*

*250n*

*252*

*252km/hr*

*2575*

*25ms*

*25n*

*26*

*26.5*

*27*

*27.0*

*27.8*

*27o*

*28*

*28.24*

*29*

*2m*

*2ms*

*2n*

*2nd*

*2v*

*2x*

*2x160*

*2xek/m*

*3*

*3.0*

*3.00*

*3.03*

*3.04*

*3.2*

*3.20*

*3.25*

*3.3*

*3.44*

*3.50*

*3.52*

*3.6*

*3.64*

*3.85*

*3.852*

*3.9*

*3.91*

*3/4*

*30*

*30.0*

*30.02*

*30/1.5*

*30/10*

*30/20*

*300*

*300/3.6*

*300/5*

*300/6*

*300kg*

*300km*

*300km/hr*

*300x2.90*

*300x3.50*

*302*

*304*

*30ms*

*30n*

*30s*

*30x50*

*31*

*315*

*315km*

*32*

*32.0*

*32.5*

*325*

*325x3.25*

*326o*

*32n*

*32o*

*33*

*33.0*

*33ms*

*34*

*34.72*

*342o*

*34o*

*35*

*35.0*

*354o*

*359kg*

*359x9.81*

*35m*

*36*

*36.0*

*36n*

*37*

*375*

*38*

*38.2*

*38.9*

*380/19.0*

*380ns*

*39*

*390.6*

*391kg*

*3ms*

*3rd*

*4*

*4.0*

*4.00*

*4.08*

*4.16*

*4.24*

*4.35*

*4.5*

*4.50*

*4.80*

*4.88*

*40*

*400*

*400kg*

*400km/hr*

*400x*

*400x1.50*

*402*

*406*

*40m*

*40n*

*412n*

*42.385*

*431*

*4333*

*450*

*450kg*

*450n*

*450x*

*460*

*460x2.50*

*47.9*

*475*

*475km*

*47n*

*480kg*

*480x22.5*

*4th*

*4x*

*5*

*5.0*

*5.00*

*5.02*

*5.20*

*5.25*

*5.252*

*5.3*

*5.50*

*5.7*

*50*

*50.0*

*500*

*500.va*

*500/3*

*500/6*

*500g*

*500kg*

*500km*

*500m*

*500n*

*500va*

*500x*

*500x0*

*500x20.0*

*500x20.02*

*500x22.02/25.0*

*500x32.0*

*500x4*

*500xv2*

*50km/hr*

*50m*

*50ms*

*50n*

*50x4.5*

*50x60*

*522*

*53o*

*54*

*54o*

*557*

*56o*

*590*

*5hr*

*5n*

*5th*

*6*

*6.0*

*6.00*

*6.2*

*6.20*

*6.25*

*6.30*

*6.31*

*6.38*

*6.51*

*60*

*600*

*600/1.5*

*600kg*

*600km*

*600x*

*600x15.0*

*600x2.65*

*600x27.0*

*60kg*

*60km/hr*

*60x60*

*615m*

*62*

*625*

*630kg*

*630kgms*

*630x10.0*

*650/100*

*650ns*

*6583*

*67*

*69.6*

*6o*

*7*

*7.00*

*7.2*

*7.29*

*7.71*

*7.85*

*70/5.0*

*700*

*700gram*

*700kg*

*700n*

*700x*

*700x24.5*

*700x8.50*

*70m*

*70m/s*

*70ms*

*70o*

*70x3*

*70x3.6*

*714n*

*725*

*727n*

*72km/hr*

*72o*

*73.8*

*735m*

*75*

*75.0*

*750*

*750/1250*

*750g*

*750kg*

*750v2*

*750x*

*750x0*

*750x10.0*

*750x15.0*

*75kg*

*75km/hr*

*7n*

*8*

*8.0*

*8.00*

*8.10*

*8.20*

*8.25*

*8.5*

*8.50*

*8.502*

*8.75*

*80*

*80.0*

*800*

*800kg*

*800n*

*800x9.81*

*80kg*

*80ns*

*810*

*815*

*820*

*820kg*

*825*

*825/50.0*

*83.3*

*840*

*848*

*850*

*850kg*

*850ms*

*850x2.15*

*87*

*9*

*9.0*

*9.00*

*9.25*

*9.68*

*9.81*

*90*

*90.0*

*90/1.5*

*90/3.6*

*900*

*900kg*

*900n*

*900x22.5*

*900x35.0*

*900x6.25*

*92*

*9467*

*950*

*994*

*9x103ns*

*a2*

*a4*

*aa*

*ab*

*abl*

*abn*

*abrupt*

*absorb*

*ac*

*acceler*

*accid*

*accident*

*accord*

*account*

*accur*

*achiev*

*acid*

*act*

*action*

*actual*

*ad*

*add*

*addit*

*advis*

*ae*

*af*

*affect*

*ag*

*agenc*

*agreement*

*ah*

*ahead*

*ai*

*air*

*airbag*

*aircraft*

*aj*

*ak*

*al*

*alien*

*allow*

*almost*

*alon*

*along*

*alreadi*

*also*

*alter*

*although*

*aluminium*

*alway*

*amount*

*analys*

*analysi*

*and/or*

*angl*

*anim*

*anoth*

*answer*

*anyth*

*apart*

*appar*

*appear*

*appli*

*appropri*

*approx*

*approxim*

*area*

*arithmet*

*around*

*arrow*

*assign*

*associ*

*assum*

*astronaut*

*astronomi*

*astrophys*

*ati*

*atom*

*attach*

*attempt*

*audio*

*audio-visu*

*aust*

*av.speed*

*avail*

*averag*

*avoid*

*awar*

*away*

*axe*

*axl*

*b*

*b2*

*back*

*backward*

*bad*

*bag*

*balanc*

*balanced/in*

*ball*

*bar*

*base*

*bear*

*becom*

*began*

*begin*

*behind*

*belt*

*bench*

*best*

*better*

*bicycl*

*bigger*

*biggest*

*bike*

*biolog*

*biota*

*bit*

*black*

*blank*

*blast*

*blow*

*blueprint*

*bodi*

*book*

*bottom*

*bottom-left*

*bounc*

*bounci*

*bound*

*box*

*brake*

*broken*

*broken-down*

*brought*

*build*

*built*

*burn*

*bus*

*c*

*cabl*

*calcul*

*call*

*came*

*campus*

*cancel*

*cannon*

*cannot*

*capsul*

*car*

*caravan*

*care*

*carriag*

*case*

*caus*

*ce*

*ceas*

*cell*

*centr*

*centripet*

*chain*

*chang*

*changeabl*

*chem.monit*

*chemic*

*chemistri*

*chican*

*choic*

*circl*

*circular*

*clear*

*cliff*

*climb*

*clockwis*

*close*

*closer*

*closest*

*co*

*coast*

*code*

*collaps*

*collid*

*collis*

*colour*

*combin*

*come*

*common*

*communic*

*compar*

*comparison*

*complet*

*complic*

*compound*

*comput*

*computer-bas*

*concept*

*concertina*

*conclus*

*condit*

*conflict*

*confus*

*connect*

*consequ*

*conserv*

*consid*

*constant*

*constitut*

*construct*

*cont*

*contact*

*contain*

*content*

*context*

*continu*

*contradict*

*contribut*

*control*

*convert*

*copi*

*copyright*

*core*

*corner*

*corp*

*correct*

*correspond*

*corros*

*cosmic*

*could*

*couldn*

*count*

*countri*

*coupl*

*cours*

*cover*

*crash*

*creat*

*creatur*

*cross*

*cross-wind*

*crumpl*

*current*

*curv*

*curvatur*

*cushion*

*cyclist*

*d*

*damag*

*dan*

*danger*

*dash*

*dashboard*

*data*

*date*

*de*

*deal*

*dealt*

*death*

*deceler*

*declar*

*decreas*

*defin*

*definit*

*delta*

*demand*

*depend*

*describ*

*design*

*destroy*

*destruct*

*detail*

*determin*

*devic*

*di*

*diagram*

*didn*

*die*

*differ*

*difficult*

*direct*

*disappear*

*dish*

*disk*

*displac*

*displacement-t*

*displacement-tim*

*displacementtim*

*display*

*dissip*

*dist/time*

*distanc*

*distance-t*

*distance-tim*

*distance/time*

*distort*

*distortion/damage*

*divid*

*divis*

*dna*

*doesn*

*done*

*dot*

*doubl*

*downhil*

*downslop*

*downward*

*drag*

*draw*

*drive*

*driver*

*drove*

*due*

*durat*

*dynam*

*e*

*e.g*

*earth*

*easi*

*easili*

*east*

*east-b*

*eastward*

*echo*

*econom*

*ecosystem*

*educ*

*effect*

*either*

*ek*

*elast*

*ele*

*electr*

*electric/magnetic*

*electron*

*element*

*elsewher*

*em*

*embank*

*employ*

*empti*

*en*

*end*

*energi*

*engin*

*enough*

*enrol*

*entir*

*envir*

*environ*

*equal*

*equat*

*equilibrium*

*equip*

*equival*

*error*

*es*

*especi*

*essenti*

*estim*

*eta*

*etc*

*even*

*event*

*everi*

*everyday*

*everyth*

*evolut*

*exact*

*exampl*

*exceed*

*exert*

*exhaust*

*exist*

*expect*

*experi*

*experiment*

*explain*

*explan*

*explos*

*extend*

*extern*

*extra*

*extra-terrestri*

*f*

*f.s*

*f.t*

*f/a*

*f/m*

*f2*

*facilit*

*fact*

*factor*

*fail*

*fall*

*familiar*

*far*

*fast*

*faster*

*fax*

*fc*

*fcr*

*featur*

*feel*

*ff*

*fi*

*field*

*figur*

*file*

*filenam*

*fill*

*final*

*find*

*fire*

*first*

*fit*

*fix*

*flat*

*flatten*

*flew*

*fli*

*flight*

*flow*

*flung*

*follow*

*forc*

*force/acceleration*

*form*

*format*

*formula*

*forward*

*found*

*four*

*fraction*

*frame*

*free*

*frequent*

*friction*

*friction/retarding*

*front*

*fuel*

*full*

*fulli*

*g*

*gain*

*gap*

*gas*

*gase*

*gate*

*gather*

*gearbox*

*general*

*generat*

*genet*

*gentler*

*get*

*give*

*given*

*go*

*goe*

*gone*

*govern*

*gr*

*gra*

*gradient*

*gradual*

*grand*

*grand-sound*

*graph*

*gravit*

*graviti*

*great*

*greek*

*grid*

*grip*

*ground*

*gun*

*h*

*halt*

*hammer*

*hand*

*hang*

*happen*

*he/she/it*

*head*

*head-on*

*head-to-tail*

*headon*

*health*

*heat*

*height*

*help*

*henc*

*high*

*higher*

*hill*

*hint*

*his/her/its*

*hit*

*hold*

*home*

*horizont*

*hour*

*howev*

*hr*

*hrs*

*hsc*

*human*

*hump*

*i.e*

*i/f*

*i/t*

*ice*

*ici*

*idea*

*ident*

*ie*

*ien*

*ignor*

*ii*

*iii*

*illeg*

*imagin*

*imaginari*

*immedi*

*immens*

*immov*

*impact*

*impal*

*implement*

*import*

*imposs*

*impuls*

*inc*

*incid*

*includ*

*increas*

*indic*

*industri*

*ineffici*

*inelast*

*inertia*

*inflat*

*inform*

*ing*

*initi*

*injuri*

*insid*

*instal*

*instant*

*instant-by-inst*

*instantan*

*institut*

*insuffici*

*inter*

*inter-c*

*intern*

*interpret*

*interv*

*intiti*

*introduc*

*invers*

*involv*

*isaac*

*issu*

*iti*

*iv*

*ive*

*j*

*join*

*jolt*

*joul*

*journey*

*jump*

*jupit*

*k*

*k.i.s.s*

*kcic*

*ke*

*keep*

*kept*

*key*

*kg*

*kg.ms*

*kgms*

*kick*

*kick-b*

*kill*

*kilogram*

*kilogram-m*

*kinet*

*kiss*

*kj*

*km*

*km.hr*

*km/hr*

*know*

*known*

*l*

*lab*

*lab.trolley*

*label*

*laboratori*

*lac*

*laden*

*land*

*landmark*

*lap*

*larg*

*larger*

*last*

*later*

*launch*

*law*

*le*

*learn*

*least*

*leav*

*left*

*leg*

*ler*

*less*

*let*

*lethal*

*letter*

*level*

*li*

*licenc*

*life*

*lift*

*light*

*like*

*limit*

*line*

*link*

*liquid*

*list*

*littl*

*live*

*loc*

*local*

*locat*

*lock*

*logo*

*long*

*longer*

*look*

*loos*

*lose*

*loss*

*lost*

*lot*

*love*

*low*

*lower*

*lta*

*m*

*m/s*

*ma*

*ma.s*

*ma.ua*

*ma.va*

*macquari*

*magnitud*

*[email protected]*

*main*

*maintain*

*make*

*mani*

*map*

*mark*

*mass*

*massiv*

*master*

*materi*

*math*

*mathemat*

*matter*

*max*

*max15.0*

*max6.25*

*maximis*

*maximum*

*may*

*mb*

*mb.ub*

*mb.vb*

*mean*

*meant*

*meanwhil*

*measur*

*memoris*

*metal*

*method*

*metr*

*metre/sec*

*metres/hr*

*metres/sec/sec*

*mg*

*micro*

*micro-sleep*

*microsoft*

*might*

*mind*

*mini*

*mini-van*

*minimis*

*minor*

*minut*

*miss*

*mitchel*

*mixtur*

*mngment*

*modern*

*moment*

*moment-by-mo*

*momentum*

*money*

*moon*

*most*

*motion*

*motionless*

*motor*

*motorbik*

*motorcycl*

*move*

*movement*

*ms*

*mu*

*mu2*

*much*

*multipl*

*multipli*

*must*

*mv*

*mv2*

*mv2/f*

*mv2/r*

*mxv*

*n*

*n.m*

*n.s*

*name*

*natur*

*near*

*need*

*neg*

*negat*

*negatv*

*neglibl*

*negoti*

*net*

*network*

*never*

*new*

*newton*

*newton-*

*newton-metr*

*newton-second*

*next*

*nm*

*non*

*non-profit*

*nonprofit*

*north*

*north-b*

*north-south*

*northbound*

*northward*

*note*

*noth*

*notic*

*nsta*

*nsw*

*nt*

*number*

*numer*

*o*

*obey*

*object*

*observ*

*obtain*

*obvious*

*occup*

*occur*

*often*

*on-screen*

*one*

*opp/adj*

*oppos*

*opposit*

*option*

*orbit*

*orient*

*origin*

*out-dat*

*outlin*

*overcom*

*overhead*

*overview*

*p*

*p.e*

*pack*

*page*

*paper*

*part*

*particip*

*particl*

*particular*

*paseng*

*pass*

*passeng*

*patch*

*path*

*pattern*

*pedal*

*peopl*

*per*

*perhap*

*period*

*perman*

*permit*

*person*

*petrol*

*photo*

*photocopi*

*physic*

*pick*

*pie*

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*www.keepitsimplescience.com.au*

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