Topic: The Scientific Process Unit 1: Chapter 1

What is the goal of Scientific Investigations? Scientific investigations: Are the heart of science Produce evidence that helps answer questions May lead to new questions Advance science

The Scientific Method-what are the steps? A generalized set of steps scientists follow Ask a question Do background research Construct a hypothesis Test your hypothesis by designing an experiment Analyzing your data and drawing conclusions Reporting your results There is no required pathway for the scientific method Sometimes steps are skipped, sometimes they are repeated

What is a hypothesis? Definitions: Potential answer to a question that can be tested by gathering information “an educated guess”

What makes a Hypothesis “Scientific” Not all hypotheses are created equal Scientific hypotheses must meet two requirements: Must be testable Must be falsifiable Testable Can be tested with observations that agree or disagree with the hypothesis Falsifiable Can be shown to be false if it really is false

Is it possible to “prove” a scientific hypothesis? It takes just one exception to disprove a scientific hypothesis Proving that a scientific hypothesis is true is essentially impossible In science we use the term support/supported to describe hypotheses that have never been disproven

What does a good experiment require? Experiments are controlled scientific studies of specific variables Variables: Factor that can take on different values There must be at least two variables in any experiment Manipulated variable (independent variable) Variable that is changed by the researcher Responding variable (dependent variable) Variable that the researcher predicts will change if the manipulated variable changes

What is an experimental control variable? Controls are variables that must be held constant so they won’t influence the outcome of an experiment If control variables are not held constant it is impossible to determine exactly what is causing your dependent variable to change

What is a “unit” and why are they important? Definition: A standard quantity used for measurement Units were invented so people could communicate amounts to each other For communication to be successful, everyone’s idea of any unit of measure must be the same

What are SI units? SI stands for International System of Units We commonly refer to it as the Metric System Almost all fields of science us metric units when gathering data Easier to work with and convert Based on prefixes

English vs. Metric (SI)

Topic: Distance, Speed, and Velocity Unit 1: Chapter 1

What is Distance and how do we measure it? Definition: Describes how far it is from one point to another Distance is measured in units of length The SI unit for length is the meter (m) Short distances are measured in centimeters (cm) Long distances are measure in kilometers (km)

What is Speed and how do we measure it? Definition: How fast or slow something moves Speed determines how far something travels in a given amount of time The SI unit for speed is meters per second (m/s) Other common units for speed Kilometers per hour (km/h) Miles per hour (mph) Centimeters per second (cm/sec)

What is Instantaneous Speed? Definition: Speed at any given instant Difficult to calculate When you look down at the speedometer, you are observing instantaneous speed

What is Average Speed? Practice: It took an airplane 3,600 seconds to travel 540 km. What was the average speed of the airplane? What is the speed of a car that traveled 75 km in 1.5 hours? Even if speed varies during a trip, it is possible to calculate average speed

Calculating Distance or Time from Speed If you know average speed you can calculate: Distance Time To calculate distance: Distance = speed x time To calculate time: Time = distance/ speed Practice: If a car travels at an average speed of 60km/h for 5 hours, what distance did it travel? If you walk 6km at an average speed of 3 km/h, how much time does it take?

Speed Triangle

Speed vs. Velocity Speed tells us how fast or slow an object is moving but nothing about direction Definition: Velocity is the measure of both speed and direction Velocity represents two components of motion: Speed Direction

How do we represent velocity? Velocity is a vector Definition: A vector is a measurement that includes both size and direction Vectors are often represented by arrows The length of the arrow stands for speed The direction the arrow points indicates direction

How do you calculate velocity? You can calculate the average velocity of and object that is not changing direction Practice: Toni’s dog is racing down the sidewalk toward the east. The dog travels 35 meters in 18 seconds before it stops running. What is the velocity of the dog?

Practice NASCAR fans love race day when they get a chance to cheer on their favorite team! If a driver was able to travel 600 miles in 3 hours, what was his average speed? The fastest car on Earth, a British-made Thurst SSC, would win every NASCAR race in America. It it takes 0.5 hours (30 minutes) to travel 380 miles, what is its speed? The fastest train on Earth, the TGV from France, can travel at faster speeds than trains in the United States. During a speed test, the train traveled 800 miles in 2.5 hours. What is its speed?

Practice Spirit of Australia, a hydroplane boat, made speed records by traveling 239 miles in 0.75 hours (45 minutes). What is its record- breaking speed? The fastest plane ever made, the Lockhead SR71, was able to travel 2200 miles per hour. Based on this speed, how far could it travel in: 2 hours? 3 hours? 5 hours?

Topic: Position-Time Graphs Unit 1: Chapter 1 and 2