Accuracy, Precission, SFs, Error and Uncertainty

Warming Up
Join the Quizziz and open ChatGPT

Multiple Choice

Is this an SI base unit: second (s)?

• Yes

• No

Multiple Choice

The speed is derived quantity

• Yes

• No

Multiple Choice

Is this an SI base unit: kilometre (km)?

• Yes

• No

Learning Objectives

I can:

1. Understand the distinction between precision and accuracy.

2. Determine the significant figure in the measurement.

3. Understand and explain the effects of systematic errors (including zero errors) and random errors in measurements.

4. Assess the uncertainty in the measurements.

Accuracy and Precision

TRUE VALUE

TARGET

Multiple Choice

This bullseye demonstrates...

• High Accuracy & High Precision

• High Accuracy & Low Precision

• Low Accuracy & High Precision

• Low Accuracy & Low Precision

Multiple Choice

?

• High Accuracy & High Precision

• High Accuracy & Low Precision

• Low Accuracy & High Precision

• Low Accuracy & Low Precision

Multiple Choice

This bullseye demonstrates...

• High Accuracy & High Precision

• High Accuracy & Low Precision

• Low Accuracy & High Precision

• Low Accuracy & Low Precision

Multiple Choice

Four students each made a series of measurements of the acceleration of free fall g. The table shows the results obtained. The true value of acceleration of free fall is 9.8 m/s². Which set of results could be described as precise but not accurate?

• A

• B

• C

• D

Four students each made a series of measurements of the acceleration of
free fall g. The table shows the results obtained. The true value of
acceleration of free fall is 9.8 m/s2. Which set of results could be described
as precise but not accurate?

The answer is D

Dropdown

The gravity is 9.8​​ m/s² . Option A is ​ ​ ​

Select answer

Dropdown

​​ The gravity is 9.8​​ m/s² .Option B is ​ ​ ​

Select answer

​

Multiple Choice

Four different students use a ruler to measure the length of a 15.0 cm pencil. Their measurements are recorded on four different charts. Which chart shows measurements that are precise but not accurate?

• A

• B

• C

• D

Significant Figures

The result of measurement is 36.8˚C

Significant Figures

known

Estimate
d

In any measurement, the number of significant figures

is the number of digits thought to be correct by the
person doing the measuring that include all of the

digits that are known, plus a last digit that is

estimated.

Significant Figures

Dropdown

In any measurement, the number of significant figures is the number of digits thought to be correct by the person doing the measuring that include all of the digits that are ​

Select answer

, plus a last digit that is estimated.

The result of measurement is 36.8˚C

Significant Figures

known

Estimate
d

36.8

3
SFs

Significant Figures Rules

1. Every nonzero digit is significant.

4 SFs

Other example:
Each of these measurements has three
significant figures:

24.7 kg, 714 m, 0.721 A

Significant Figures Rules

2. Zeros appearing between nonzero digits are

significant. These are called “sandwich zeros”.

3 SFs

Other example:
Each of these measurements has four
significant figures.

7003 meters, 40.79 seconds,
1.503 grams

Significant Figures Rules

3. Trailing zeros follow a non zero digit and are

significant only if there is a decimal point.

Examples of this rule with the zeros this rule affects in
boldface:
0.00500 A has 3 SFs.

0.03040 s has 4 SFs.

2.30 x 10^(-5)nm has 3 SFs.

4.500 x 10^(12) kg has 4 SFs.

100.000 g has 6 SFs.

Significant Figures Rules

4. Unlimited number of significant figures
There are two situations in which numbers have an unlimited
number of significant figures. Counting and Equivalents.

The first involves counting. 23 people in your classroom
This measurement is a counted value, so it has an unlimited
number of significant figures.

Multiple Choice

How many significant figures: 216 m

• 1

• 2

• 3

• 0

Multiple Choice

How many significant figures: 2016 m

• 1

• 2

• 3

• 4

Multiple Choice

How many significant figures: 153.0 mL

• 1

• 2

• 3

• 4

Multiple Choice

How many significant figures: 0.012 km

• 1

• 2

• 3

• 4

Multiple Choice

How many significant figures: 0.001 g

• 4

• 3

• 2

• 1

Multiple Choice

How many significant figures: 4.20 cm

• 1

• 2

• 3

• 4

Error of Measurement

Error

● Systematic Error
● Zero Error
● Random Error

Open Ended

Find in ChatGPT, what is a systematic error in measurement? Drop the definition in ChatGPT in the resoponse.

Open Ended

Find in ChatGPT, what is a zero error in measurement?

Open Ended

Find in ChatGPT, what is a Random error in measurement? Drop the definition in ChatGPT in the resoponse.

Poll

Read the definition of a systematic error in the book. (Page 305)

In your opinion, do you agree on the definition in ChatGPT and in the book are the same?

• strongly agree

• agree

• neutral

• disagree

• strongly disagree

Poll

Read the definition of a zero error and random error in the book. (Page 305)

In your opinion, do you agree on the definition in ChatGPT and in the book are the same?

• strongly agree

• agree

• neutral

• disagree

• strongly disagree

Multiple Choice

Systematic errors lead to a lack of:

• accuracy in the measurement.

• significant digits in the measurement.

• precision in the measurement.

• gradation of the measuring instrument

Multiple Choice

Random errors lead to a lack of:

• accuracy in the measurement.

• significant digits in the measurement.

• precision in the measurement.

• gradation of the measuring instrument

Multiple Choice

What kind of error is Parallax error or the viewing consistently from the wrong angle for all readings?

• Systematic errors

• Random errors

• Both systematic and random errors

• Neither systematic nor random errors

Multiple Choice

Repeated measurements of a quantity can reduce the effects of

• both random errors and systematic errors

• neither random errors nor random errors

• random errors

• systematic errors

Match

Match the following terms with the correct definition.

• Random error

• Systematic error

• Calibration

• Multiple Measurement

Error because of observer

Error due to measurement tool.

A way to reduce systematic error

The way to reduce random error

• Error because of observer

• Error due to measurement tool.

• A way to reduce systematic error

• The way to reduce random error

Uncertainty of Measurement

Uncertainty

There is always a degree of uncertainty when measurements are
taken; the uncertainty can be thought of as the difference between
the actual reading taken (caused by the equipment or techniques
used) and the true value.

Time measurement using pendulum (bob)

Write measurement results of a quantity

Finding The Value Uncertainty

Reading
Repeating reading

Finding The Value Uncertainty Through Reading

For an analogue scale, the uncertainty is ± half of the
smallest scale division.
For a digital scale, the uncertainty is ± 1 in the least
significant digit.

Multiple Choice

What is the temperature and uncertainty indicated by this thermometer?

• 24.0 ± 0.5 °C

• 24.05 ± 0.05 °C

• 24 ± 1 °C

• 28.0 ± 0.1°C

Finding The Value Uncertainty

Reading Analog:

The uncertainty of measurement in a reading measurement (analog)=
½ smallest division

Reading Digital:
The voltmeter on the left has a
digital scale. The least
significant digit is the 8. The
uncertainty from reading this
scale is ± 0.1 volts.

Reading Digital:
The voltmeter on the left has a
digital scale. The least
significant digit is the 8. The
uncertainty from reading this
scale is ± 0.1 volts.

Finding The Value Uncertainty

Repeated the reading:

The uncertainty in repeated data: half the range i.e. ± ½ (largest -
smallest value)

Example:
A length is measured five times with a ruler whose smallest division is 0.1 cm
and the readings obtained, in cm, are: 22.9, 22.7, 22.9, 23.0, 23.1. What is
the reading obtained and the uncertainty?

Example:
A length is measured five times with a ruler whose smallest division is 0.1 cm and
the readings obtained, in cm, are: 22.9, 22.7, 22.9, 23.0, 23.1. What is the reading
obtained and the uncertainty?

Answer the questions in your book pg. 308, no. 9 a-d

Book Activity

Tech activity

Analyze the uncertainty of your measuring period results (spreadsheet) in previous experiment.

Stage :

1.Find Max value

command” =MAX( )

2.Find the Min value
command” =MIN( )

3.Subtract Max-Min and divided it by 2