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Let’s talk about feet…… FOOT LAB!!!!. Accuracy and Precision. The Goal Measure the distance across the room as precisely as you can using “feet” as your units of measurement. Resources Strip of adding machine tape  Your foot. How many feet: Presentation.

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Presentation Transcript

• The Goal

• Measure the distance across the room as precisely as you can using “feet” as your units of measurement.

• Resources

• Strip of adding machine tape

Be prepared to present your results to the class when called upon. I will ask you 3 questions.

What was your method for getting the measurement?

How did you maximize the precision?

• Accuracy is the real deal; the truth; the accepted value

• Precision has two meanings:

• How repeatable the measurements are (range)

• How small the interval of measurement is

• In the foot lab, what aspect of precision was being investigated?

• What do you think the goal is in science regarding accuracy and precision?

• What is the correct way to take and record a measurement?

Parallax and Precision

ParallaxAn apparent shift in position of an object when it is viewed from different angles

Location, location, location! Align eyes directly with indicator to increase accuracy.

PrecisionHow long is the blue line?

0 ft

1 mm

2 mm

Always estimate one place beyond smallest interval.

What is the length of the blue line?

Quantitative measurements – involve actual numbers (quantities)

These depend on reliability of the measuring instrument.

These depend on care with which it is read.

Numerical Portion

Unit

Measurements REQUIRE measurement?Units of Measure

The standards of measurement used in science are those of the metricsystem.

The metric system is also known as the International System of Units (SI), established in 1960.

This system’s focus is simplicity and is based on 10 or multiples of 10.

cm, mm, km or m

In Physics these are the most prevalent units of mass used

• g or kg

Prefixes measurement?

One last thing - about measurement?ROUNDING

In Chemistry, you learned about Significant Figures, or Sig Figs. They relate to the precision of the measurement being taken.

In Physics, we won’t focus on Sig Figs as much. We will round answers to nearest tenth or possibly hundredth, so your answers will look like XX.X or XX.XX

Also, round at the end of computation only.

SCIENTIFIC METHOD measurement?

• What are the steps of the Scientific Method?

• Make a hypothesis, or educated guess.

• Perform an experiment to test hypothesis.

• Analyze the data from the experiment.

• Form a conclusion. Did you prove or disprove your hypothesis?

SCIENTIFIC METHOD measurement?

Why do we care?

Effective in gaining, organizing, and applying knowledge

An organized approach in studying problems

Who is considered the “Father” of the Scientific Method?

Who is this? measurement?

Galileo

1600s

Founder of Scientific Method

Principle of Inertia

Father of Astronomy, Physics, Modern Science

Controversy: Heliocentrism (opposed Aristotle, Copernicus, and the Church)

Order of Operations measurement?

When there is more than one operation involved in a mathematical problem, it must be solved by using the correct order of operations .

Remember, calculators will perform operations in the order which you enter them, therefore, you will need to enter the operations in the correct order for the calculator to give you the right answer.

PLEASE EXCUSE MY DEAR AUNT SALLY measurement?or justP.E.M.D.A.S.Parentheses

OOO Practice Problems measurement?

18

2 x 3 =

OOO Practice Problems measurement?

18

(2 x 3) =

18

6 = 3

OOO Practice Problems measurement?

2[14 – 32] =

OOO Practice Solutions measurement?

2[14 – 32] =

2[14 – 9] =

2[5] =

= 10

Dimensional measurement?Analysis

Used to convert between different units of measurement

This is done by multiplying by factors of 1

What do you have?

What do you want?

Is your answer going to be larger or smaller than the starting number?

What do you know?

Remember you must be able to cancel out all units except the one you want to end up with

Step 1 analysis

Write down the number and unit that you are starting with

Step 2 analysis

Find out how to arrive at your final unit by using known conversion factors

Step 3 analysis

Set up your conversion factor so that the units cancel

Example analysis

Convert 5 m into km:

Step 2: you need to get to km

Step 3: you know that: 1km = 1000 m

Step 4:

5 m X 1km =

1000 m

0.005m

**Always multiply every number across the top ,then multiply every number across the bottom. Finally divide the product of the top by the product of the bottom. Record number and unit.