How Science works : Graphs

Teachers Notes This sequence of slides is designed to introduce, and explain, the idea of Graphs in practical work, as explained on pages 363-364 in New Physics for You, 2006 & 2011 editions or later. Note : When you start this PowerPoint if you see a message about Read-only embedded fonts then you are recommended to select Open Read-Only as this (i) gives a clearer font for those at the back of the room and (ii) ensures that the text-highlighting of key words is correct. On each slide the key points are revealed step by step, at the click of your mouse (or the press of a key such as the space-bar). Before making the next mouse-click you can ask questions of the class or make statements about what is about to be revealed. This should help students to become clearer about the ideas involved.

Naturally it pays to have quick practice-run first. To start the slide-show, press function-key F5 (or right-click->Full Screen) (to return to normal view press the key). For more (free) PowerPoint presentations, visit How Science works: Graphs New Physics for You, pages 363-4 Learning Objectives You should learn :

About different types of graphs, How to draw them when you are doing your practical work, How to interpret the different shapes. Drawing a graph When should and when I drawI draw

a should a bar-chart ? ? line-graph Drawing a graph Look at the table of your results: If this column has only certain fixed values, use a bar-chart:

a continuous range of values, use a line-graph: Drawing a graph What is the best way to draw a line-graph? 5 steps in drawing a graph 1. Choose simple scales. For example: 1 large square = 1 newton (1 N)

or 1 large square = 2 N, or 5 N, or 10 N But never choose an awkward scale, like 1 square = 3 N or 7 N Choose a scale that will make your graph use most of the sheet of paper. 5 steps in drawing a graph 1. Choose simple scales. Put the dependent variable on the y-axis

and the independent variable on the xaxis 5 steps in drawing a graph 2. Plot the points neatly. To mark the points we usually use an X x x x Usually you need 5 or more

points for the graph. x x x Re-check each one before your next step. 5 steps in drawing a graph

3. If the points form a straight line draw the best straight line through them li n f o e x

s be t fi t x x x x

x Check that it looks the best straight line. 5 steps in drawing a graph 4. If the points form a curve draw a free-hand curve of best fit Do not join the points like a dot-todot. 5 steps in drawing a graph

5. If a point is not on the line use your apparatus to check this measurement again x x x This is called an anomalous point. x

x x You can decide to ignore anomalous points. 5 steps in drawing a graph In summary: 1. Choose good scales, with the dependent variable on the yaxis 2. Plot the points carefully 3. Draw a line of best fit using a ruler for a straight line graph, 4. or draw free-hand for a curved graph

5. Check anomalous points. Types of graphs Lets look at some examples of graphs Types of graphs 1 length length

A straight line graph: weigh t An example would be the length of a spring against the weight on it. weight

Types of graphs 2 A special case is when the straight line goes through the origin : origin In this case the two quantities are directly

proportional. If one doubles, then the other one also doubles. Types of graphs 2 If you think your graph should go through the origin, then draw it exactly through the origin.

Types of graphs the extension of a spring against the weight on it. extension Example 1: 2

weight Types of graphs the current in a resistor against the p.d. across it. current Example

2: 2 voltag e This illustrates Ohms Law. Types of graphs 3 A curved graph, rising :

The dependent variable rises quickly at first Here are some examples: and then more slowly Types of graphs

the velocity of a falling object against the time. velocity Example 1: 3 time Eventually the object will reach its terminal velocity.

Types of graphs the current in a filament lamp against the p.d. current Example 2: 3

voltag e Types of graphs 4 A curved graph, falling : The dependent variable falls quickly at

first and then more slowly Here are some examples: Types of graphs the activity of a radioactive source against the time. activity

Example 1: 4 tim e The time to fall to half is called the halflife. acceleration Types of graphs Example

2: 4 the rate of change is shown by the gradient of the graph. tim e This is discussed in the next PowerPoint.

Learning Outcomes You should now: Know how to draw a line-graph correctly, Be able to give examples of graphs with different shapes, Be able to interpret graphs with different shapes. For more details, see: New Physics for You, page 364, 391

For more free PowerPoints, visit the web-site at If you are connected to the web at the moment, click below to see whats available:

Recently Viewed Presentations

  • PowerPoint Presentation

    PowerPoint Presentation

    Thames Magistrates' Court ex p Polemis [1974] 1 WLR 1371 Judicial Review 3 Exceptions to this rule: Public Interest : R v. Gaming Board for Great Britain ex p Benaim and Khaida [1970] 2 All ER 528. National Security :...
  • Honors English 3 October 27 -

    Honors English 3 October 27 -

    I can edit sentences for mistakes in mechanics. I can relate a work of literature to the time period in which it is set and in which it is written. I can demonstrate comprehension of increasingly difficult texts by answering...
  • Muscles of the Head, Neck, and Face

    Muscles of the Head, Neck, and Face

    paralysis causes face to sag. found in scalp, forehead, around the eyes, nose and mouth, and in the neck. 10-Muscles in Facial Expression. Figure 10.7a. ... fix hyoid bone from below…allowing suprahyoid muscles to open mouth . omohyoid - depresses...


    Taxonomy doesn't have this problem because it is simply known as Agkistrodonpiscivorus Swedish botanist who developed the two word naming system known as binomial nomenclature. He developed groups or taxa to distinguish organisms based on their characteristics.
  • Introduction of the chain-linking method to the compilation ...

    Introduction of the chain-linking method to the compilation ...

    Introduction of the annual overlap method to the compilation of Bulgarian quarterly national accounts ... the annual overlap method can be found by looking at the difference between this method and the over-the-year method in GDP growth. 15 February 2007...
  • Dissolve Definition: to melt away or break apart

    Dissolve Definition: to melt away or break apart

    Dissolve. Martha was desperate to dissolve her marriage with Daniel because she wanted to move on with her. life and forget about him. Synonym: Antonym:
  • Input & Output

    Input & Output

    Return code vs. Exceptions. Unlike Exception, type for "return code" should match with method's return type. Exception logically goes directly to the code where it is handled, but what happens actually?
  • There are 2 types of cells in the

    There are 2 types of cells in the

    Fig 14.18 Fig 14.15 Sensory Pathway Motor Pathway Interneuron (Integration) CNS PNS Receptors Effector Tissue 1. Sensory Neuron 3. Motor Neuron 2. Interneuron A typical Neuron Anaxonic Bipolar Unipolar Multipolar Telodendria The Anatomy of a Motor Neuron Axolemma (outermost surface...