Distance and Displacement Power Point
Transcript of Distance and Displacement Power Point
1© Manhattan Press (H.K.) Ltd.
• Position and distancePosition and distance
Position, distance and Position, distance and displacementdisplacement
• Position and displacementPosition and displacement• TimeTime
• Scalar and vector quantitiesScalar and vector quantities
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study motions of bodies
How? How?
Why?Why?
Position and distance
1. position
2. direction
3. time taken
4. other related physical quantities
MechanicsMechanics
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Position and distance
• position — denotes both the direction & distance from a given reference point
• unit of distance: metre (m) / kilometre (km)
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1 km north
Shopping centre X from Chris:direction: northdistance: 1 km
1 km east
Shopping centre X from Tracy:
direction: east
distance: 1 km
Chris
Tracy X
Y
N
1 km
1 km
1 km 1 km
position of Tracy
position of Chris
Position of shopping centre X
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direction = south-east
distance = km
= 1.41 km
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The position of church Y from Chris:
Chris
Tracy
Y
N
1 km
1 km
1 km 1 km
Position of church Y
X
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direction = south-east
distance = km
= 2.83 km
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The position of church Y from Tracy:
Chris
Tracy
X
Y
N
1 km
1 km
1 km 1 km
Position of church Y
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destination
starting point
• Distance from destination = 200 m
• Distance from starting point (complete 1 loop) = 400 m
The reference point
200 m
200 m
Different reference point Position changes
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Position and displacement
• Distance alone is not enough
Distance = 5 m, represents A or B?
O BA5m 5m
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Position and displacement
• represents change in position
How can we solve it
Displacement
• a physical quantity which has both
magnitude & direction
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Position and displacement
Displacement of A and B from O:
O BA
direction direction
negative (–) positive (+)
5 m 5 m
Magnitude = 5 m
Direction:
• Left ()
• Right(+)5 m +5 m
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Position and displacement
magnitude of displacement = shortest distance between starting point & end point
• independent of the travelled path
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Position and displacement
distance
length
independent of the travelled path
length
depend on the travelled path
displacementdistance
displacementThinking 1Thinking 1
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Time
Measure the duration of an event
Unit: second (s), minute (min), hour (h)
a sundial
an atomic clock
a watcha quartz clock
a stopwatch
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time, distance
& temperature
Scalar and vector quantities
magnitude only
scalar quantity vector quantity
magnitude & direction
displacement