Modules 1 & 2 - Foundation - Definitions

Question 1

Absolute Uncertainties

Answer 1

The interval that a value is said to lie within, with a given level of confidence.

Question 2

Accuracy

Answer 2

A measure of how close a measurement is to the true value.

Question 3

Analogue Apparatus

Answer 3

Measuring apparatus such as rulers, beakers and thermometers that rely on the experimenter reading off a scale to determine the measurement.

Question 4

Anomalies

Answer 4

Data points that don’t fit the pattern of the data.

You should determine why an anomalous result has occurred before removing it.

Repeat readings help remove anomalies.

Question 5

Control Variables

Answer 5

Variables that must remain the same throughout an experiment so as to not affect the results.

Question 6

Dependent Variable

Answer 6

The variable being measured in an experiment. It is dependent on the independent variable.

The dependent variable should be plotted on the y-axis of a graph

Question 7

Digital Apparatus

Answer 7

Measuring apparatus such as ammeters, voltmeters and digital calipers that digitally measure and display a measurement.

Question 8

Fiducial Marker

Answer 8

A thin marker, such as a splint, that is used to ensure readings are taken from the same place each time

They are used to improve the accuracy of measurements.

Question 9

Gradient

Answer 9

The change in the y-axis value over the change in the x-axis value between two points.

If the graph is curved, a tangent can be drawn to calculate the gradient at a specific point.

Question 10

Independent Variables

Answer 10

The variable that is changed by the experimenter in an experiment.

The independent variable should be plotted on the x-axis of a graph.

Question 11

Line of Best Fit

Answer 11

A line drawn on a graph to demonstrate the pattern in the plotted data points.

Question 12

Percentage Uncertainties

Answer 12

The uncertainty of a measurement, expressed as a percentage of the recorded value.

Also known as relative uncertainties.

Question 13

Plumb line

Answer 13

A string with a weight used to provide a vertical reference line

Question 14

Precision

Answer 14

A measure of how close a measurement is to the mean value. It only gives an indication of the magnitude of random errors, not how close data is to the true value.

Question 15

Prefixes

Answer 15

Added to the front of units to represent a power of ten change

Question 16

Quantities

Answer 16

Physical properties such as length, force, potential difference, field strength etc. Not to be confused with units.

Question 17

Random Errors

Answer 17

Unpredictable variation between measurements that leads to a spread of values about the true value.

Random error can be reduced by taking repeat measurements.

Question 18

Rate of change

Answer 18

How much of something happens per unit time (e.g. each second)

Question 19

Relative Uncertainties

Answer 19

The uncertainty of a measurement, expressed as a percentage of the recorded value.
Also known as percentage uncertainties.

Question 20

Repeatable

Answer 20

The same experimenter can repeat a measurement using the same method and equipment and obtain the same value.

Question 21

Reproducible

Answer 21

An experiment can be repeated by a different experimenter using a different method and different apparatus, and still obtain the same results.

Question 22

Resolution

Answer 22

The smallest change in a quantity that causes a visible change in the reading that a measuring instrument records.

Question 23

Resolution of Forces

Answer 23

The splitting of a force into its horizontal and vertical components.

Question 24

Scalar Quantities

Answer 24

A quantity that only has a magnitude, without an associated direction.

Examples include speed, distance and temperature.

Question 25

SI Base Units

Answer 25

The standard units used in equations, which cannot be stated in any other more simple units.

They are: metres (m), kilograms (kg), seconds (s), amps (A), Kelvin (K), moles (mol) and candela (cd).

Question 26

SI Units

Answer 26

The standard units used in physics equations, such as Newtons (N), Joules (J), Volts (V).

These units can be stated in terms of the equivalent SI Base Units (e.g. 1 N = 1 kg m s‾²) by looking at the equations relating the physical quantities (e.g. F = ma)

Question 27

Significant Figures

Answer 27

A measure of a measurement’s resolution.

All numbers except zero are counted as a significant figure.

When zeros are found immediately after a decimal place, they too are counted.

When doing a calculation, the number of significant figures you give your final answer to shouldn’t be more than the least number of significant figures of the input values.

Question 28

Systematic Errors

Answer 28

Causes all readings to differ from the true value by a fixed amount.

Systematic error cannot be corrected by repeat readings, instead a different technique or apparatus should be used.

Question 29

Triangle of Forces

Answer 29

A method of finding the resultant force of two forces.

The two forces are joined tip to tail and the result is then the vector that completes the triangle.

Question 30

Vector Addition

Answer 30

Finding the total effect of all vectors by joining them tip-to-tail and finding the resultant of the vector that joins the start point of the first vector to the end point of the final vector.

It does not matter which order you add the component vectors, the resultant vector will always be the same.

Question 31

Vector Components

Answer 31

Taking a vector and splitting it into two perpendicular components, which if added together tip-to-tail would give the original vector.

Taking vector components is often useful when resolving forces, considering projectile motion, or when calculating work done.

Question 32

Vector Quantities

Answer 32

A quantity that has both a magnitude and an associated direction. Examples include velocity, displacement and acceleration.

Question 33

Vernier Scales

Answer 33

The type of scale used on calipers and micrometers, that involve reading from a fixed scale and a moving scale to produce accurate measurements.

Question 34

Zero Errors

Answer 34

A form of systematic error, caused when a measuring instrument doesn’t read zero at a value of zero. This results in all measurements being offset by a fixed amount.