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