Foundations for PhysicsDr. Gluck

Unit 1.1Laws of Motion, Velocity, Displacement, and

AccelerationPS 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 MotionDescribing the Physical Universe

1.1 What is Physics?

1.2 Distance and Time

1.3 Speed

Chapter 1.1 Objectives and Vocabulary

natural lawexperimentanalysismasssystemvariablemacroscopicscientific methodindependent variabledependent variablehypothesiscontrolled variable experimental variablemodel

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.

Universe

Everything around us

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 of a SystemEnergy 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 heightLOW POTENTIAL

ENERGY

1A Investigation: Time, Distance, and Speed

Key Question:

How is motion described and measured in Physics?

*Students read text section 1.2AFTER 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

distancelengthEnglish systemmetric systemtime intervalsecond

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.

Three Three targets with targets with three arrows three arrows each to each to shoot.shoot.

Can you hit the bull's-eye?Can you hit the bull's-eye?

Both accurate and precise

Precise but not accurate

Neither accurate nor precise

How do they How do they compare?compare?

Can you define accuracy vs. precision?Can you define accuracy vs. precision?

AccuracyCloseness to the true value

PrecisionReproducibility of results

Our measurements:

1.must be precise (reproducible)2.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

1.A particular moment (12:00 pm)

2.A quantity of time (3 hours)

3. Time Interval – “how much time did it take…?”

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

ANSWER:13,510 seconds

Independent variable

Dep

en

den

t vari

ab

le

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 TopicsMeasure 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

speed

constant speed

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.

What does this sign tell you??

25 miles per hour

25 miles hour

“per” means “divide”

Speed (v=d/t)Distance divided by time.

•If you follow the speed limit, you will travel 25 miles in 1 hour.

Is a ratio: a relationship between distance and time

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