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 Concepts:
 Distance, time, displacement, motion, point of reference, relative
position,
 origin, slope (gradient), speed, acceleration, deceleration
 States of motion, at rest, accelerating, decelerating, constant speed
 Skills:
 Draw distancetime graphs for motions relative to different points of
reference
 Describe speed as change of distance per unit time
 Relate slope of distancetime graph to speed
 Relate shape of distancetime graph to the four states of motion—rest,
acceleration, deceleration and constant speed

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 Skills:
 Draw distancetime graphs for motions for different points of reference
 Describe and calculate speed as change of distance per unit time

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 Motion is relative.
 While quietly listening to your teacher talking in the classroom you are
all at rest relative to one another.
 Each one of you is at a different distance from the board, and from
each other.
 At rest relative to the rest of your classmates means that you are not
changing your position relative to any other classmate of yours.
 You are at a fixed distance from every single other classmate.
 You teacher however may not be at rest relative to you all; he may be
moving about the room.

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 However, relative to the sun in the sky you are NOT at rest.
 Since you are all part of plant earth which revolves around the sun,
you are moving relative to the sun.
 (Similarly, relative to the earth, the sun is in motion too.)
 If you were waiting by the road for a friend watching the cars go by,
relative to the house in front of you, you would not be in motion, you would be at rest.
 The cars are however are in motion, relative to you they are moving.
 The people in the class are also in motion relative to you.
 But the driver of the car and the passenger are not in motion relative
to one another!
 As far as they are concerned, you are in motion relative to them!!

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 The point is that an object can be at rest or in motion depending on the
reference point.
 Whether you are in motion or the house in motion or the car in motion or
the people in the car are in motion depends on the reference point.
 When you are the reference point, the car and its occupants are said to
be in motion while the house is not.
 When the car is the reference point, you are in motion and so is the
house, but the occupants of the car are not (because they are also
moving with the car) etc. etc.
 Relative motion can be represented using distancetime graph.

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 In motion…but at constant speed.

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 1) On which part of the journey was the cyclist travelling at the
fastest speed?
 2) What speed was the cyclist travelling on this part of the journey?
 3) How many metres had the cyclist travelled after 30 seconds?
 4) What was the speed of the cyclist over part E of the journey?
 5) Was the cyclist travelling at a faster speed at point A or E of
the journey?
 6) Calculate the average speed for the whole journey.

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 In motion…and accelerating

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 In motion…but decelerating

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 Concepts
 Ticker timer, ticker tapes, constant speed, accelerating, decelerating,
ticker tape chart
 Skills
 Be able to determine the state of motion of an object based on the way
the dots appear on a ticker tape
 Interpret ticker tape charts—identify motion of object as constant
speed, acceleration and deceleration from the ticker tape chart
 Be able to calculate the speed of an object from ticker tape data on
the motion of the object

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 Ticker Timers are gadgets used in science to investigate how things
move.
 A ticker timer puts 50 dots every second onto a piece of tape (referred
to as a ticker tape).
 The tape can be fixed to a moving object.
 The object pulls the tape through the timer.
 The way that the dots appear on the tape gives us clues about the motion
of the object.
 There are four different ways the dots may appear.

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 They could appear close together like shown above.
 That means that the object was moving slowly.

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 3. They could appear unequally spaced as above and the spacing may be
increasing towards the end of the tape.
 That means the object was accelerating

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 In the lab you will obtain ticker tapes that show three different
motions:
 Constant speed,
 Acceleration and
 Deceleration.
 The “object” in motion will just be your hand pulling the ticker tape
through the ticker timer.
 Essentially, you will have to pull the ticker tape through the timer in
such a way as to get the three variety of motion.
 A ticker tape showing constant speed and acceleration should be
relatively easy.
 What about deceleration?
 Next, you will organize the ticker tapes graphically, like histograms.

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 1. Cut out the tape into strips of 10 dots. Cut through the first dot
and then count 10 dots and cut through the 10^{th} one. In other
words, don’t count the first dot. You’ll end up with 10 spacings.

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 Chart was created using only 5 dots for ease!

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 This could represent the motion of a parachutist.

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 Since the ticker timer makes 50 dots each second, then the distance
between two dots is the distance covered in 1/50 = 0.02 seconds.
 In other words, the ticker times takes 0.02 seconds between each dots.
 That is,

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 Another way of calculating speed given the same information is thus:
 Since the gap between two dots is 10 cm, distance covered by 50 dots (in
1 s) = 10 cm ´ 50 = 500 cm
 \Speed = 500 cm/s

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 Given distance information that spans more than two dots,

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 You will get the ticker tapes for the frictionless motion of a trolley
on a plank pulled along by a free falling weight.
 The trolley will accelerate as it rolls along the plank.
 You are going to investigate the effect of mass of trolley and the mass
pulling it on the acceleration of the trolley.
 In other words, you will attempt to answer the following question:
 How does the mass pulling a trolley and the mass of trolley affect the
acceleration of a trolley?

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 You will first get a ticker tape for the motion of a single trolley (of
1 kg ) pulled by a 100g mass suspended at the other end of the plank
hanging from a pulley.
 Next you will get a ticker tape for the motion of two trolleys (one
piled on the other) pulled along by a 200g mass suspended at the other
end of the plank.
 You will then cut the tapes into pieces of 5 dots. REMEMBER TO CUT ALONG
THE 5^{TH} DOT AND NOT BETWEEN THE 5^{TH} AND THE 6^{TH}
DOT!!

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 Paste the pieces of tapes on a graph paper side by side leaving a cm of
space between them.
 In your notebook, state a hypothesis for how the acceleration of the two
trolleys will vary.
 In other words, how the slope (gradient) of the two histograms will
compare, and therefore, how the mass of trolley and the weight (force)
pulling it will affect the acceleration.
 Draw the histograms for the motion of the two trolleys that you would
expect to get based on your hypothesis.
