Pp Iaa Science Skills
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IAA Science Skills These are the skills that you need when doing an IAA in Science
Writing the correct units for any measurement Example : What are these measured in? Time
s
Distance
m
Speed
m/s
Energy
J
Power
W
Wavelength
m
Frequency
Hz
Using scientific words properly Example : What are the scientific words for these? Hotness
Temperature
Movement energy Kinetic energy Height energy
Gravitational potential energy
Hot air rising
Convection
Pull of gravity
Weight
Amperage
Current
Writing answers to 3 significant figures What are these numbers to 3 significant figures? A : 4.50241
4.50
B : 156.845
157
C : 0.00024654 D : 1.9999
0.000247 2.00
Judging which of two versions of an experiment is better and why Example : Which is better? Take each measurement several times and calculate an average or We don’t always ask you to do it as this takes quite a lot of timeone measurement taken each time If you try repeating a measurement when you start you may find you don’t need to take an average time / s 12.2, 12.2, 12.2, 12.2
Know which is the independent variable and which is the dependant variable in an experiment These are the headings for a table in an experiment where the time for a ball to drop is timed h/cm
t/s
t/s
t/s
Avg t/s
Which is the independent variable? How do you know Height, h, as it is put in first in equal steps Which is the dependant variable? How do you know Time ,t, as this depends upon the height All other variables must be controlled e.g. ball mass
Check for anamolous results and do not use them Which is the anamolous result in this table? h/cm
t/s
t/s
t/s
Avg t/s
10.0
0.56
0.61
0.55
0.57
20.0
0.80
0.81
0.83
0.81
30.0
1.21
1.25
1.23
1.23
40.0
1.44
2.89 1.45
1.48
50.0
1.78
1.83
1.80
1.94 1.47 1.46 1.80
measurement again IfEven this better, result istake not the used, the answer is more reliable
Calculating an average How do you work out the average of 3, 4 and 5? Add them up and divide by the number of numbers Average = (3 + 4 + 5) / 3 = 12 / 3 = 4 What is the average of these 5 temperatures? T / oC : 12.5
12.8
13.6
Total = 63.8 Average = 63.8 / 5 Average temperature = 12.8 oC
11.5
13.4 Remember 3 significant figures and units
Drawing an accurate graph and take readings from it
YES NO!! NO!! YES
Taking a graph reading showing what you are doing What is P when Q = 20.0s ? When Q = 20.0s P = 12.4 cm?
P/cm
12.4
3 significant figures and units
20
Q/s
Describing the pattern shown by a graph Describe the pattern shown by this line Imagine that you are walking up the line as a hillside A C
As D gets bigger C As A smaller gets bigger gets with the Bslope increases with the becoming slope getting less steeper
B D
Understanding how to make a conclusion more valid Get rid of anomolous results by repeating them Could it be straight? Could it be a curve? Getting more results would help Getting a wider range of results would help Almost certainly a straight line
Understanding how to make a result more reliable You take a measurement
t = 12.2 s
You take the same measurement again
t = 14.5 s
These are quite widely different so they are not very reliable You can improve reliability by take several readings and working out an average t / s = 12.2, 14.5, 11.8 More reliable
Average = 12.8 s 3 significant figures and units
There are also some general skills that you need to do in situations that you may not have come across before: Judging whether measurements are accurate Working out what errors there are in an experiment Suggesting better equipment to use and explaining why it is better Suggesting how an experiment can be improved
Suggesting how an experiment can be improved One way to do this is to look at the things being measured – usually 1 independent and 1 dependent What is the smallest accurate measurement that you could take for the independent variable? What is the smallest measurement that you could take for the dependent variable? Which of these should you concentrate on improving?
Suggesting how an experiment can be improved Example : An experiment is done to find out how hot water gets after heating it for 40.0 s. It reaches 5 oC. The stop clock measures to the nearest 0.1 s 100 x 0.1 / 40 = 0.25 %
A very accurate reading
The thermometer measures to the nearest 1 oC 100 x 1 / 5 = 20%
A large amount
It would help if the temperature measurement was taken 3 times and an average was calculated Even better, use a more accurate thermometer – one measuring to 0.1 oC (now 2 %)
Calculate using standard form What is the answer to these? ANSWERS A : 2.34 x 102 x 3.56 x 103
8.37 x 105
B : 4.56 x 104 / 8.12 x 105
0.0562 = 5.62 x 10-2
C : 2.34 x 10-12 x 9.56 x 10-13
2.24 x 10-24
Remember to write out to 3 significant figures
Writing the correct units for any measurement Example : What are these measured in? Time
s
Distance
m
Speed
m/s
Energy
J
Power
W
Wavelength
m
Frequency
Hz
Using scientific words properly Example : What are the scientific words for these? Hotness
Temperature
Movement energy Kinetic energy Height energy
Gravitational potential energy
Hot air rising
Convection
Pull of gravity
Weight
Amperage
Current
Writing answers to 3 significant figures What are these numbers to 3 significant figures? A : 4.50241
4.50
B : 156.845
157
C : 0.00024654 D : 1.9999
0.000247 2.00
Judging which of two versions of an experiment is better and why Example : Which is better? Take each measurement several times and calculate an average or We don’t always ask you to do it as this takes quite a lot of timeone measurement taken each time If you try repeating a measurement when you start you may find you don’t need to take an average time / s 12.2, 12.2, 12.2, 12.2
Know which is the independent variable and which is the dependant variable in an experiment These are the headings for a table in an experiment where the time for a ball to drop is timed h/cm
t/s
t/s
t/s
Avg t/s
Which is the independent variable? How do you know Height, h, as it is put in first in equal steps Which is the dependant variable? How do you know Time ,t, as this depends upon the height All other variables must be controlled e.g. ball mass
Check for anamolous results and do not use them Which is the anamolous result in this table? h/cm
t/s
t/s
t/s
Avg t/s
10.0
0.56
0.61
0.55
0.57
20.0
0.80
0.81
0.83
0.81
30.0
1.21
1.25
1.23
1.23
40.0
1.44
2.89 1.45
1.48
50.0
1.78
1.83
1.80
1.94 1.47 1.46 1.80
measurement again IfEven this better, result istake not the used, the answer is more reliable
Calculating an average How do you work out the average of 3, 4 and 5? Add them up and divide by the number of numbers Average = (3 + 4 + 5) / 3 = 12 / 3 = 4 What is the average of these 5 temperatures? T / oC : 12.5
12.8
13.6
Total = 63.8 Average = 63.8 / 5 Average temperature = 12.8 oC
11.5
13.4 Remember 3 significant figures and units
Drawing an accurate graph and take readings from it
YES NO!! NO!! YES
Taking a graph reading showing what you are doing What is P when Q = 20.0s ? When Q = 20.0s P = 12.4 cm?
P/cm
12.4
3 significant figures and units
20
Q/s
Describing the pattern shown by a graph Describe the pattern shown by this line Imagine that you are walking up the line as a hillside A C
As D gets bigger C As A smaller gets bigger gets with the Bslope increases with the becoming slope getting less steeper
B D
Understanding how to make a conclusion more valid Get rid of anomolous results by repeating them Could it be straight? Could it be a curve? Getting more results would help Getting a wider range of results would help Almost certainly a straight line
Understanding how to make a result more reliable You take a measurement
t = 12.2 s
You take the same measurement again
t = 14.5 s
These are quite widely different so they are not very reliable You can improve reliability by take several readings and working out an average t / s = 12.2, 14.5, 11.8 More reliable
Average = 12.8 s 3 significant figures and units
There are also some general skills that you need to do in situations that you may not have come across before: Judging whether measurements are accurate Working out what errors there are in an experiment Suggesting better equipment to use and explaining why it is better Suggesting how an experiment can be improved
Suggesting how an experiment can be improved One way to do this is to look at the things being measured – usually 1 independent and 1 dependent What is the smallest accurate measurement that you could take for the independent variable? What is the smallest measurement that you could take for the dependent variable? Which of these should you concentrate on improving?
Suggesting how an experiment can be improved Example : An experiment is done to find out how hot water gets after heating it for 40.0 s. It reaches 5 oC. The stop clock measures to the nearest 0.1 s 100 x 0.1 / 40 = 0.25 %
A very accurate reading
The thermometer measures to the nearest 1 oC 100 x 1 / 5 = 20%
A large amount
It would help if the temperature measurement was taken 3 times and an average was calculated Even better, use a more accurate thermometer – one measuring to 0.1 oC (now 2 %)
Calculate using standard form What is the answer to these? ANSWERS A : 2.34 x 102 x 3.56 x 103
8.37 x 105
B : 4.56 x 104 / 8.12 x 105
0.0562 = 5.62 x 10-2
C : 2.34 x 10-12 x 9.56 x 10-13
2.24 x 10-24
Remember to write out to 3 significant figures
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