2 Foundations Of Physics

Question 1

Independent variable

Answer 1

The variable for which value is changed or selected by the investigator

Question 2

Dependent variable

Answer 2

The variable of which the value is measured for each and every change in independent variable

Question 3

Control variable

Answer 3

A variable which, in addition to the IV, affects the outcome of the investigation so has to be kept constant or monitored

Question 4

Interval

Answer 4

Quantity between readings

Question 5

Reproducible

Answer 5

If the investigation is repeated by another person or by using different equipment or techniques and the same results are obtained

Question 6

Repeatable

Answer 6

If the original experimenter repeats the investigation using the same method and equipment and obtains the same results

Question 7

Hypothesis

Answer 7

A proposal intended to explain certain facts or observations

Question 8

Resolution

Answer 8

The greater the resolution of the measuring instrument is, the smaller the smallest increment that can be measured to e.g. a metre ruler marked off in mm has greater resolution than one marked in cm

Question 9

Error

Answer 9

The difference between the measured value and the true value of the thing being measured

Question 10

Uncertainty

Answer 10

A quantification of the doubt about the measured result

Question 11

Random error

Answer 11

Humans and the equipment have limitations

Question 12

Systematic error

Answer 12

that does not happen by chance but instead is introduced by an inaccuracy in the apparatus or its use by the person conducting the investigation.
o Zero Error: an error that occurs when the apparatus shows a non-zero value when it should be registering a value of exactly zero.
o Parallax Error: an error produced whenever a scale, gauge, or pointer is observed wrongly during scientific experimentation due to position of viewing and perception.

Question 13

SI meaning

Answer 13

International system of units

Question 14

The six SI base units

Answer 14

Length- m
Mass- kg
Time- s
Electric current- A
Temp- k
Amount of substance- mol

Question 15

What’s a derived unit

Answer 15

A unit that can be worked out from the base units

Question 16

Prefixes

Answer 16

Peta 
Tera
Giga 
Mega
Kilo
Deci
Centi
Milli
Micro
Nano 
Pico 
Femto

Question 17

Peta

Answer 17

10^15

Question 18

Tera

Answer 18

10^12

Question 19

Giga

Answer 19

10^9

Question 20

Mega

Answer 20

10^6

Question 21

Kilo

Answer 21

10^3

Question 22

Deci

Answer 22

10^-1

Question 23

Centi

Answer 23

10^-2

Question 24

Milli

Answer 24

10^-3

Question 25

Micro

Answer 25

10^-6

Question 26

Nano

Answer 26

10^-9

Question 27

Pico

Answer 27

10^-12

Question 28

Femto

Answer 28

10^-15

Question 29

Homogeneity of physical equations

Answer 29

It is said that an equation is homogenous if both sides of the equations can be simplified to the same base unit or set of base units. This means that the equation could be correct, as long as there are no numerical errors made. If an equation is not homogenous then it is incorrect.

Question 30

Accuracy

Answer 30

An experiment is accurate if the quantity being measured has a value that’s very close to the commonly accepted or true value.

Question 31

Precision

Answer 31

The results of an experiment are precise if they are close together and have a small range. The smaller the range of the repeated values, the higher the precision. The term precision is linked to the spread of the data or the percentage uncertainty in a measurement. A precise experiment has a smaller spread in the data or the smaller the uncertainty.

Question 32

Single readings uncertainty

Answer 32

If single readings have been taken then the uncertainty should be the smallest interval or division on the measuring instrument. Consider the example below. o Example: A metre rule is used to measure the length of a book. uncertainty in the measuring instrument (the ruler) = ± 1mm length = (295 ± 1) mm

Question 33

Percentage uncertainty

Answer 33

Percentage Uncertainty = (Uncertainty/Average value ) x 100 o Referring back to the previous example about the ruler, The percentage uncertainty in the length is % uncertainty = ± (1/295) x 100 = ±0.34%

Question 34

Multiple readings uncertainty

Answer 34

If multiple readings have been taken then half of the range of the readings will be the uncertainty in the measured or calculated quantity.

Question 35

Readings versus measurements

Answer 35

Readings: No zero error Uncertainty is half resolution Examples: measuring cylinder, weighing scales, thermometer Measurements: Zero error Uncertainty is resolution Examples: ruler, protractor, stopwatch

Question 36

Adding or subtracting uncertainties rule

Answer 36

Add absolute uncertainties

Question 37

Multiplying or dividing uncertainties rule

Answer 37

Add percentage uncertainties

Question 38

Raising an uncertainty to a power rule

Answer 38

Multiply percentage uncertainties by the power

Question 39

How to determine the uncertainty in a gradient

Answer 39

a. Error bars may be added to each plotted point if the data points are not too scattered. b. Draw a best fit line through the scattered points (or through the error bars). The worst acceptable line is then drawn. This will either be the steepest or shallowest line. c. Determine the gradient of the best fit line and the gradient of the worst acceptable line. d. Uncertainty = |gradient of best fit line – gradient of worst acceptable line|. e. The percentage uncertainty in the gradient can be determined as follows:  Percentage Uncertainty = (Uncertainty/Gradient of best fit line) x 100

Question 40

Working out error bars

Answer 40

If each stage in iv is repeated for several results, squad all results Find range of repeats When drawing- half uncertainty

Question 41

What is a scalar quantity

Answer 41

quantity which only has magnitude

Question 42

What is a vector quantity

Answer 42

quantity that has both magnitude and direction.

Question 43

Scalar quantity examples

Answer 43

``` Mass Time Temperature Length Speed Energy ```

Question 44

Vector quantity examples

Answer 44

``` Displacement Force Velocity Acceleration Momentum ```

Question 45

How to remember base SI units

Answer 45

``` Kelvin Kills Small Angry Mole Men ```

Question 46

True value=

Answer 46

Observed value + error

Question 47

Observed value=

Answer 47

True value + random error + systematic error