Foundations for Physics Dr. Gluck Unit 1.1 Laws of Motion, Velocity, Displacement, and Acceleration PS 3-(9-11)-8a Text Chapter 1: Describing the Physical Universe

Guiding Questions How is adding displacement different from adding distance? How is calculating speed different from calculating velocity? How is determining velocity different than determining speed or acceleration? How can we determine position, speed, or velocity from a graph?

Forces and Motion Describing the Physical Universe 1.1 What is Physics? 1.2 Distance and Time 1.3 Speed

Chapter 1.1 Objectives and Vocabulary natural law experiment analysis mass system variable macroscopic scientific method independent variable dependent variable hypothesis controlled variable experimental variable model Explain what makes up the universe. Describe how the scientific method is used. Explain the effects of energy on a system.

What is Physics? Finding the simplest and least complicated explanation. Observe HOW things work. Form connections between cause and effect.

Has the ability to cause change Everything around us Universe Matter Energy Has mass and volume Has the ability to cause change

Frame of Reference System to determine or measure position based on the motion/position of the observer.

Natural Laws All events in nature obey natural laws. Natural laws do not change. Consistency - reliability of successive results or events Accuracy - how close is the result to the true value? Natural laws are based on human experiences.

Experimentation - carefully designed simulations that are used to analyze (interpret and understand) natural laws. Experiments have variables - factors that effect the behavior of the experimental system. 2 types of variables: Experimental - looked at in the experiment Independent Variable – controlled by YOU Dependent Variable – changes based on IV Control - something to compare the experimental variable to..

What are the variables? Independent variable Dependent variable

System- collection of matter and processes that occur in a certain space and can be studied.

Energy is the ability to cause change. Energy of a System Energy is the ability to cause change. Energy can take on many forms. The forms of energy can change from one to another but the TOTAL amount of energy in a system is CONSTANT.

Systems in nature want to be stable. Stability is important. In nature, stability means LOW ENERGY. Therefore, in nature, systems tend to go from higher energy levels toward lower energy levels in order to reach stability. This is true in all aspects of science.. HIGH E = UNSTABLE LOW E = STABLE

Car is unstable due to its height. HIGH POTENTIAL ENERGY Car is more stable at a lower height LOW POTENTIAL ENERGY

1A Investigation: Time, Distance, and Speed Key Question: How is motion described and measured in Physics? *Students read text section 1.2 AFTER Investigation 1A

1A Investigation Topics Learn uses and functions of CPO Timer and photogates. Set car to travel at constant speed. Measure time intervals. Calculate speed from time interval measurements. Graph position vs. timer for car traveling down track.

Chapter 1.2 Objectives and Vocabulary Express distance measurements in both English and metric units. Measure time intervals in mixed units. Distinguish between independent and dependent variables. Construct graphs. Convert between different units of time. distance length English system metric system time interval second

Can you hit the bull's-eye? Three targets with three arrows each to shoot. Both accurate and precise Precise but not accurate Neither accurate nor precise How do they compare? Can you define accuracy vs. precision?

Accuracy Precision Closeness to the true value Reproducibility of results

DISTANCE TIME Our measurements: must be precise (reproducible) Should be accurate (as close to the true value as possible) 3. must have units to communicate value In physics, we use two common measurements: DISTANCE Amount of space between two points Measured in units of length TIME A particular moment (12:00 pm) A quantity of time (3 hours) 3. Time Interval – “how much time did it take…?”

ANSWER: 13,510 seconds Convert 3:45:10 into seconds. 3 hrs x 3600 sec = 10,800 sec hr 45 min x 60 sec = 2,700 sec min = 10 sec

Dependent variable Independent variable

1B Investigation: Systems, Energy and Change Key Questions: Why do things change? Why do things change by only a certain amount? *Students read text section 1.3 AFTER Investigation 1B

1B Investigation Topics Measure time intervals. Calculate speed from time interval measurements. Identify variables in an experiment. Identify dependent and independent variables. Control variables in an experiment. Compare speeds and energy of car.

Chapter 1.3 Objectives and Vocabulary Define speed. Express an object's speed using various units. Calculate speed, distance or time given two of the three quantities. List the steps for solving physics problems. speed constant speed

What does this sign tell you?? Your text here 25 miles per hour 25 miles hour “per” means “divide” RATIO

Speed (v=d/t) Distance divided by time. Is a ratio: a relationship between distance and time If you follow the speed limit, you will travel 25 miles in 1 hour. d v t