movement in one dimension - wordpress.com · 03/07/2018  · a crow flies 10km east for 1 hour and...

MOVEMENT IN ONE

DIMENSION

Sutherland High School

CAPS

POSITION

THIS IS THE PLACE WHERE AN OBJECT IS RELATIVE TO A REFERENCE POINT.

A REFERENCE POINT IS A POINT FROM WHICH THE POSITON OF THE OBJECT IS MEASURED.

SYMBOL: 𝑥

SI UNIT: 𝑚

VECTOR

3m 1m

Example 1

Example 2

5m3.7m

1.3m

FRAMES OF REFERENCE

• Frames of reference gives a better description of motion.

• It depends where you are at that moment when using the reference point.

• The most common frame of reference for most of our movements is the earth.

• E.g. cars on the highway, throwing ball on train etc.

The difference: 𝑥 and ∆𝑥

•𝑥 = the actual position.

•∆𝑥 = change in position.

DISTANCE

DISTANCE IS THE TOTAL LENGTH OF THE ROUTE.

SYMBOL: 𝒅

Si Unit: 𝒎

SCALAR QUANTITY

DISPLACEMENT IS THE SHORTEST

DISTANCE BETWEEN START AND

FINISH.

SYMBOL IS 𝒙 AND 𝒚SI UNIT: 𝒎VECTOR QUANITY

DISPLACEMENT

Study definitions on

pg. 164

Example 3

10km east

6km west

WHAT IS THE CROWS DISPLACEMENT?

WHAT DISTANCE DID THE CROW FLY?

Example 4SOLDIERS GO ON A MARCH IN THE

DESERT. THEY FIRST WALK 6KM WEST,

REST A BIT, THEN 10KM EAST, REST A BIT,

AND THEN 2KM WEST.

1. CALCULATE THE DISTANCE COVERED.

2. CALCULATE THE DISPLACEMENT.

3. CALCULATE THEIR POSITON AT THE

SECOND REST STOP.

HOMEWORKEXERCISE 15 PG. 168-169

SPEED• The rate at which an object covers a distance.

• Distance and time is scalar – speed is scalar.

• 𝑣 =𝐷

∆𝑡

• Constant / uniform speed = speed does not change. This means that it covers equal distances in equal time intervals. This is not a common occurrence.

• Average speed = total distance divided by total time. This does not tell you how fast you are going at any moment in time.

• 𝑣𝑎𝑣𝑒 =𝐷

∆𝑡or 𝑣 =

𝐷

∆𝑡

Example 1

THE CROW FLIES IN 10KM IN 2 HOURS.

WHAT IS THE CROW’S SPEED?

VELOCITY• The rate of change of an objects position or the displacement

divided by the time taken.

• Displacement is a vector = velocity is a vector.

• 𝑣 =∆𝑥

∆𝑡

• Constant / uniform velocity = magnitude and direction must be the same. Travels in a straight line.

• If speed changes = velocity changes.

• If direction changes = velocity changes.

• Average velocity = total displacement divided by total time.

• 𝑣𝑎𝑣𝑒 =∆𝑥

∆𝑡or 𝑣𝑎𝑣𝑒 =

∆𝑦

∆𝑡

Example 2

6km west

A CROW FLIES 6KM WEST AND DOES SO IN 7MIN.

WHAT IS THE CROWS VELOCITY?

Example 3

10km east

6km west

A CROW FLIES 10KM EAST FOR 1 HOUR

AND THEN TURNS AROUND AND FLIES

6KM WEST FOR 40MIN.

WHAT IS THE CROW’S SPEED FOR THE TOTAL JOURNEY?

WHAT IS THE CROW’S VELOCITY FOR THE TOTAL JOURNEY?

Pick a

partner

and

solve.

CONVERSION

𝑘𝑚. ℎ−1 𝑚. 𝑠−1

÷ 𝟑. 𝟔

x 𝟑. 𝟔

homeworkExercise 16 pg. 175-176

ACCELERATION• The rate of change of an objects velocity.

• Velocity is a vector = acceleration is a vector.

• 𝑎 =∆𝑣

∆𝑡=

𝑣𝑓−𝑣𝑖

∆𝑡

• Constant / uniform acceleration = there is a constant increase in velocity in every equal time interval.

• Acceleration can be positive or negative.

• If the acceleration and velocity is in the same direction – the object is speeding up.

• If the acceleration and velocity is in the opposite direction – the object is slowing down

Example 4

A CAR STARTS FROM REST AT A STOP STREET. AFTER 𝟓𝒔 THE CAR HAS A

VELOCITY OF 𝟕𝒎𝒔−𝟏 . CALCULATE THE ACCELERATION OF THE CAR.

WHILE TRAVELLING AT A SPEED OF 𝟏𝟎𝒎. 𝒔−𝟏 ON A STRAIGHT ROAD, THE

CAR SUDDENLY HAS TO STOP FOR A RED LIGHT. IT TAKES THE CAR 6

SECONDS TO COME TO A STOP. CALCULATE THE ACCELERATION.

TICKER TIMERSExercise 17 pg. 189-192

IMPORTANT FACT: MOTION FOR TICKER TIMERS CAN ONLY BE LEFT AND RIGHT. NOT NORTH, EAST, SOUTH OR WEST!