Maths skills Flashcards
(25 cards)
When is a line of best fit drawn
Enough data points to accurately detect a pattern in data
When are lines on a graph drawn dot to dot
Not enough data points on the graph (intermediates) to accurately detect a pattern in data
Limitations of experiments
End point could be subjective = inaccurate measurements of time taken etc
Water bath not thermostatically controlled = decreased overtime
Not enough intermediate values taken to find optimum etc
Range of values not wide enough
HCl use in root tip squash + waterbath
Softens and loosens root tissues
Uncertainty
+- the smallest scale division on the apparatus
How to calculate percentage error
Using measurement uncertainty
Percentage error
Uncertainty x number of times read
divided by measurement taken
x100
How to reduce uncertainty of measurements
Increase resolution of an instrument eg reads to millimetres not just micrometres (has smaller scale divisions)
Take multiple readings eg measure total length of multiple objects as opposed to individually
Repeat measurements
Reading vs measurement
Values derived from a single judgement eg temperature of a thermometer = reading
Values taken as the difference between 2 judgements so recorded to be the distance = measurement
Uncertainty of a reading
+- Half of the smallest scale reading
Uncertainty of a measurement
+- the smallest scale reading
(half the smallest scale reading x2)
Equipment that makes 1 judgement
thermometer
pH meter
Balance (scales)
Measuring cylinder
Equipment that makes 2 judgements
Ruler
Stopwatch (stop start)
Calculate uncertainty without information on the resolution
+- the most significant digit
Why does taking multiple instances of measurements reduce uncertainty?
Instead of the uncertainty being total uncertainty of all measurements
It is the uncertainty of 1 measurement divided by number of objects
Why does it work to take multiple instances of measurements to reduce uncertainty?
Because the percentage uncertainty of multiple measurements of objects at once = percentage uncertainty of one measurement of a singular object
Uncertainty of repeated measurements mean
Half of the range of values
Percentage uncertainty
Uncertainty/value x 100
Percentage uncertainty in a repeated measurement
Uncertainty/mean value x100
uncertainty if values are added together/ found difference between them
The uncertainties are added together
Percentage uncertainty if values are multiplied together
Percentage uncertainties are added together
Percentage uncertainty if values are divided
Percentage uncertainties are added together
Describe the graph
State differences in mean
State peaks/plateu/rate of reaction
Use the graph to explain
Describe the graph then explain what happens using own knowledge
