Unit 1 Motion and Forces
Lecture:
Covering chapter 1
CHAPTER 1
The Scientific Method
• 6 steps• 1. State the problem• 2. Research• 3. Form hypothesis• 4. Test hypothesis• 5. Analyze data• 6. Draw conclusions
Hypothesis
• A hypothesis is a testable statement
• It is NOT a question
• Ex: My plant will grow taller when it is given milk than when it is given water.
Experiments
• Your hypothesis is tested in your experiment
• In the experiment you will have an independent variable
• As it changes, it affects the dependent variable
• Ex: the taller I am (independent) the farther I jump (dependent)
Constants and Controls
• The variables that do not change in your experiment are called constants
• Ex: which melts faster, sugar or ice?• Constant: flame, container, distance to heat
source• A control is what you use to compare your
experiment to• Ex: Medicated group compared to the
placebo group
Theory verses Law
• Theory• Explanation• Has undergone a
great deal of testing• Can be changed and
adapted as needed
• Law• Explains how natural
phenomena works• Always gets the same
results
SI System of Measurement
• Length meter m
• Mass gram g
• Time second s
• Temperature kelvin k
Common SI prefixes
• Kilo- 1,000 (bigger)
• 1 kilogram = 1,000 grams
• Milli- 0.001(smaller)
• 1,000 milligrams= 1 gram
• Centi- 0.01 (smaller)
• 100 centimeters = 1 meter
Converting between units
• How many milligrams are in 60 kilograms?
• How many centimeters are in 15 millimeters?
Volume
• Volume is the amount of space an object takes up
• Volume= length × width × height
• Know that 1mL = 1 cm3
• What is the volume of an object which measures 5cm by 15cm by 20 cm?
Density
• Density is mass divided by volume
• Mass is measured in grams
• Volume is measured in cm3 or mL
• What is the density of an object that weighs 10g and has a volume of 2mL?
Kelvin and Celsius
• Kelvin is the SI unit for temperature
• To calculate Kelvin, simply add 273 to the temperature in Celsius
• Absolute zero is 0 Kelvin
• Absolute zero therefore is -273°Celsius
Line graphs vs. Bar graphs
• Line graphs are used to measure data compared to time
• The X axis is time (horizontal)
• The Y axis varies (vertical)
• Bar graphs are used to compare data
• Pie graphs are used to compare percentages