ISA Skills

Question 1

Accepted Value

Answer 1

The value of the most ACCURATE measurement available.

Sometimes called the true value

Question 2

Accuracy

Answer 2

Measure of confidence in a measurement.

Expressed as an upper and lower limit (eg 9.8+-0.3ms^-2)

Question 3

Dependent variable

Answer 3

The variable which value changes as a result of a change in the independent value.
Usually plotted on the y-axis

Question 4

Error

Answer 4

The difference between a measurement and its accepted value.
NOT a mistake made in taking a reading

Question 5

Indenpendat variable

Answer 5

Physical quantities whose values are controlled by the experimenter.
Plotted on the x and affects the dependant

Question 6

Linearity

Answer 6

constant gradient and y=mx+c can be used

Question 7

Mean vlaue

Answer 7

Calculated by adding the readings and dividing by the number of readings

Question 8

Percentage uncertainty

Answer 8

(uncertainty)/(mean value)*100

Question 9

Precision

Answer 9

The degree of “exactness”(Number of sig figs) to which a measurement can be obtained consistently

Question 10

How does one calculate the precision of a measurement that has multiple values (mean value)

Answer 10

Take half the max range

Question 11

What is the precision of an instrument

Answer 11

The smallest non-zero reading that can be meau

Question 12

Random error

Answer 12

Errors with no pattern or bias.
Are unpredictable.
Effect of these errors are reduced by taking more values

Question 13

Range

Answer 13

Difference between smallest and largest values of a set

Question 14

Reliability

Answer 14

The extent to which measurements of a quantity remain consistent over repeated measurements of the same quantity under the same conditions.

Question 15

How can one find the reliability from a graph

Answer 15

Look how close the measurements are to the best fit line

Question 16

Why use the gradient rather than a point to find the value of a quantity

Answer 16

using just one point is very unreliable and the more points you take, the more accurate the results become. a gradient is essential a multitude of points in one

Question 17

How does one calculate gradient from a graph

Answer 17

= change in y/change in x *must use at least an 8cmx8cm triangle

Question 18

How many sig figs should a value be given to

Answer 18

The minimum used but always more than 1

Question 19

Systematic error

Answer 19

error which is the same throughout an experiment e.g. background radiation

Question 20

Parallax error

Answer 20

error in readings caused by the shifting position of the observer, relative to the measuring device

Question 21

When is parallax particularly an issue

Answer 21

in measuring curved edges

Question 22

What does a parallax error imply for the uncertainty in a measurement

Answer 22

Always higher than it would be otherwise