practical skills

Question 1

why should you keep variables constant

Answer 1

so the experiment being carried out is a fair test

Question 2

what is a control variable

Answer 2

variables kept constant in a experiment

Question 3

what is a independent variable

Answer 3

the thing you change in an experiment

Question 4

dependent variable

Answer 4

the thing you measure in an experiment

Question 5

what is true about every numerical measurement

Answer 5

they have an experimental uncertainty

Question 6

what is the smallest uncertainty you can have

Answer 6

half one division on the measuring instrument used

Question 7

with a thermometer where one division is 2 degrees what will a measurement of 30 degrees be measured to

Answer 7

30 ± 1

Question 8

what does the ± sign mean

Answer 8

range which the true value lies in

Question 9

what is the uncertainty when measuring with a ruler

Answer 9

double the smallest uncertainty

Question 10

why do you have to double the uncertainty when using a ruler

Answer 10

because you measure at each end of the object so there’s uncertainty at each end

Question 11

what are two types of error

Answer 11

random error and systematic error

Question 12

what does random error do to readings

Answer 12

cause readings to be spread about the true value

Question 13

what do what does systematic error do to readings

Answer 13

cause each reading to be different by the same amount which affects the accuracy of your results

Question 14

how can you reduce uncertainty

Answer 14

*repeat each measurement
*take mean of repeated measurements
*bigger uncertainty means bigger range
*eliminate anomalous results
* use equipment with smaller intervals
*use computers and data loggers
*calibrate equipment

Question 15

how to work out fractional uncertainty

Answer 15

divide uncertainty by measurement

Question 16

how do you work out percentage uncertainty

Answer 16

divide uncertainty by measurement and multiply by 100

Question 17

when adding or subtracting data what do you do to uncertainties

Answer 17

add absolute uncertainty

Question 18

when multiplying or diving data what do you do to the uncertainties

Answer 18

add absolute uncertainties

Question 19

when raising data to the power what do you do to the uncertainty

Answer 19

times uncertainty by power

Question 20

what do error bars show

Answer 20

uncertainty of individual point

Question 21

how do u calculate the uncertainty using graphs

Answer 21

the different between the best and worst graph

Question 22

what is true about uncertainty and signifiant figures

Answer 22

you always have to round your data your uncertainty to the same number of sf as the data with the least number of sf

Question 23

when drawing graphs where should the dependent and independent variable go

Answer 23

dependent on the y axis
and independent on the x axis

Question 24

what are words you should use to show what the data shows

Answer 24

*precision
*repeatable
*reproducible
*valid
*Accurate

Question 25

what does precision mean

Answer 25

precision is the amount of reliability the smaller the amount your data spreads from the mean the more precise it is and depends on the amount of random error

Question 26

what does repeatable mean in terms of data

Answer 26

you can repeat an experiment and get the same result

Question 27

what does reproducible mean in terms of data

Answer 27

someone else can recreate your experiment using different equipment or methods

Question 28

what does valid mean in terms of data

Answer 28

original question is answered using the precise data

Question 29

what does accurate mean in terms of data

Answer 29

result is really close to the true answer