After this lesson: You can name the 5 senses off the top of your head NASK – OBSERVING VS...
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Transcript of After this lesson: You can name the 5 senses off the top of your head NASK – OBSERVING VS...
After this lesson:
You can name the 5 senses off the top of your head
NASK – OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
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Eyes (seeing)
Ears (hearing)
Nose(smelling)
Mouth(tasting)
Skin (feeling)
inaccurate!!
NASK – WAARNEMEN VS METEN
Senses
NASK – OBSERVATION VS MEASURING AND UNCERTAINTY OF MEASUREMENT
Our eyes can be fooled
Stare at the middle of the disc
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This is NOT a video!!
NASK – OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
Our eyes can be fooledLes 3 / 10
All the brown sections in this picture are
equally brown
NASK – OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
Our eyes can be fooledLes 3 / 10
NASK – OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
And our skin?
Can you, for example, feel with your skin if something is hot or cold?
What does the cold water tap feel like after a hot shower?
And what does the same cold water tap feel like after cycling in the winter?
Is the temperature different then?
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NASK – OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
Can we measure time?
How many seconds does it take before the traffic lights turn green?
start
8 seconds
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NASK – OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
We can measure this, for example, with our body, but not so accurately
Which measuring instruments do we use for this?
distanceruler, measuring tape
timestopwatch, clock
temperaturethermometer
weightscales
But are these instruments accurate?
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NASK – OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
How accurate is a stopwatch?
Now measure the time of the traffic lights with a stopwatch
start
6 seconds
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NASK – – OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
How accurate is a stopwatch?
A number of example measurements
Attempt Time (seconds)
1 6.38
2 6.39
3 6.31
4 6.37
5 6.35
6 6.40
7 6.36
8 6.41
9 6.38
10 6.34
What can you say about this?
1. All the measurements are wrong
2.All the measurements are nearlywrong
3. The measurements are very similar
4. The average is 6.37 5. The written value is pointless
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NASK The written value is pointless
Measuring seems a lot like shooting at a target
The middle is 6 seconds
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NASK – OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
Four archers
A B
C D
Who is the winner?
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NASK – OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
Four archers
A B
C D
Who is the winner?
Who would have won if only the first shot had been fired?
Who is better A or B?
Who are we?
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NASK OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
How accurate is a stopwatch?
If I know the correct value, can I revise it
Attempt Time (seconds) Correction
1 6.38 – 0.37 6.01
2 6.39 – 0.37 6.02
3 6.31 – 0.37 5.94
4 6.37 – 0.37 6.00
5 6.35 – 0.37 5.98
6 6.40 – 0.37 6.03
7 6.36 – 0.37 5.99
8 6.41 – 0.37 6.04
9 6.38 – 0.37 6.01
10 6.34 – 0.37 5.97
average 6.37 6.00
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NASK – OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
Exact
C D
Accurate Exact Accurate
Exact Accurate Exact Accurate
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NASK OBSERVING VS MEASURING AND UNCERTAINTY OF MEASUREMENT
AssignmentUsing a stopwatch, measure 10 times the time it takes for light A to change colour. Write these measurements down in a table in your notebook.
Determine the average of these measurements
Determine the level of inaccuracy
Now measure 10 times the time that light B takes to change colour. Write these measurements down in a second table.
Determine the level of accuracy
Correct the average with the inaccuracy level of A
A B5 seconds ??
How long does traffic light B take?
6.5 seconds
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