PHYSICAL SCIENCEPresenting Scientific Data

CREATING AND INTERPRETING GRAPHS

Many people have pets. One survey of pet owners showed the following breakdown of the type of pets owned: 35% dogs; 35% cats; 10% birds; 5% hamsters, gerbils, mice, rats; 5% reptiles; and 10% other.

1. Copy the incomplete circle graph below on your paper.

Complete the graph using the survey data. Estimate the

angle of each section of your completed circle graph. Give your graph a title and label what each section of the graph represents.

2. Explain how viewing the graph conveys information to the reader more quickly than reading the list of data.

PREVIEWING

a. Variable y is plotted vs. variable x. b. Showing how a variable responds to changes in another

c. Scaled bars used to represent d. Comparing a similar various measurements set of datae. A divided circle, with each “slice” f. Showing how a part relates to representing a proportional fraction the whole

DATA TABLES

Using a table is a simple way to present data visually.

The table relates two variables – a manipulated variable (location) and a responding variable (average annual precipitation).

LINE GRAPH

Plotting the mass of water against the volume of water yields a straight line.

What is the volume of 3g of water?

3cm3

What is the mass of 9 cm3

of water?9g

Useful for showing changes that occur in related variables.

Slope = Rise/Run

‘rise’ = change in the y-variable

‘run’ = change in the x-variable

IMPORTANT VOCABULARY

The mass of the water is directly proportional to the volume, meaning that the ratio of two variables is constant. (if one goes up, the other goes up)

An inverse proportion is a relationship in which the product of 2 variables is a constant = (if one goes up, the other goes down)

Each point on the graph above represents the same volume of water: 1 gallon.

BAR GRAPHS & CIRCLE GRAPHSUseful for comparing several measurements, amounts of changes.

Shows how a part or share of something relates to the whole.

CELSIUS, KELVIN AND FAHRENHEIT

(1) Celsius Scale – widely used in chemistry and the everyday scale of temperature in most countries. 0C is the freezing point of water 100C is the boiling point of water at sea

level.

CELSIUS, KELVIN AND FAHRENHEIT

(2) Kelvin Scale – is the SI scale and is based solely on the properties of gases. Used in most calculations. 0 (zero) is the lowest attainable

temperature on this scale and is referred to as ABSOULUTE ZERO. It is equivalent to –273.15C. On the Kelvin scale water freezes at 273 K and boils at 373 K.

CELSIUS, KELVIN AND FAHRENHEIT

(3) Fahrenheit Scale – the common temperature scale in the United States which is not generally used in scientific studies. Water freezes at 32F and boils at 212F.

CELSIUS, KELVIN AND FAHRENHEIT

You will need to know how to convert among all three temperature scales. These are the formulas that you will need to MEMORIZE!

K = C + 273.15  C = 5/9 ( F - 32)  F = 9/5 ( C) + 32

 *Remember to always do what is in parenthesis

first!

TEMPERATURE CONVERSION EXAMPLE

Liquid nitrogen, which is often used as a coolant for low-temperature experiments, has a boiling point of 77K. What is the temperature on the Fahrenheit scale?

First convert 77K to Celsius: Tc=Tk-273.15 = 77-273.15= -196oC

Next convert Celsius to Fahrenheit F = 9/5 ( C ) + 32 F = 9/5 (-196oC) +32 = -320.8 F