A*

Question 1

Precision

Answer 1

How close results are to each other

Question 2

Accuracy

Answer 2

How close results are to true value

Question 3

Error

Answer 3

Difference between individual results and true value

Question 4

Uncertainty

Answer 4

Interval within which the true value can be expected to lie for a measurement

Question 5

Absolute uncertainty

Answer 5

•Resolution of a measuring instrument

Smallest value •  ———————
         2

Question 6

Percentage uncertainty 
 (SINGLE READING)

Answer 6

Absolute uncertainty
• —————————— x 100
measured value

• %U is smaller for larger objects

Question 7

Percentage uncertainty 
 (MULTIPLE READINGS)

Answer 7

Half the range
• ——————— x 100
Mean

Question 8

Combined uncertainty 
 (Add & subtract)

Answer 8

Add ABSOLUTE uncertainty

Question 9

Combined uncertainty 
 (Multiply & Divide)

Answer 9

Add PERCENTAGE uncertainty

Question 10

5 types of error

Answer 10

• Random
• Systematic
• Human
• Measurement
• percentage

Question 11

Random error

Answer 11

Error caused by unknown and unpredictable changes in experiment

E.g changes in rate of heat loss due to wind

Question 12

Human error

Answer 12

Error caused as a result of being human

E.g reaction time

Question 13

Systematic error

Answer 13

• Zero - instrument not reading 0 When quantity measured is 0
• scale factor - instrument reads changes to be greater or less than actual changes in measurement

Question 14

Measurement error

Answer 14

Caused by difference between measured value and true value

Question 15

Percentage error

Answer 15

Calculated value-actual value
————————————— x100
Actual value