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Do Now…• Quest will start in a minute… You

have 5 minutes to do any last minute preparation!!

• Everyone should TAKE A RULER to keep from the teacher’s desk.

• If you need to BORROW a calculator, please trade for one now.

• **If you did not turn in your Metric Patrol last class, do it now! (10% off each day it is late!**)

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When you are done with Quest…1. Place quest in “In Box” on desk; return ruler!

2. Take a copy of the Pre- Assessment; Do your best to complete based on what you already know BEFORE learning the chapter

a. Place in OTHER basket on teacher’s desk when done

3. THEN …Take a copy of vocab. Use your textbook - Ch. 2 - to complete Vocab silently after quest– it is HW it is HW if you do not finish in class (5 points)

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You can describe the motion of an object by its position, speed, direction, and acceleration.

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An object is moving if its position relative to a fixed point is changing.

2.1 Motion Is Relative

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Even things that appear to be at rest move.

When we describe the motion of one object with respect to another, we say that the object is moving relative to the other object. (in other words, from the perspective of the other object)

2.1 Motion Is Relative

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The racing cars in the Indy 500 move relative to the track.

2.1 Motion Is Relative

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Although you may be at rest relative to Earth’s surface, you’re moving a little more than 100,000 km/h relative to the sun.

• A book that is at rest, relative to the table it lies on, is moving at about 30 kilometers per second relative to the sun.

• The book moves even faster relative to the center of our galaxy...but just how fast?

2.1 Motion Is Relative

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FYI…FYI…

http://www.enchantedlearning.com/subjects/astronomy/planets/earth/Speeds.shtml

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• Unless stated otherwise, the speeds of things in our environment are measured relative to the surface of Earth.

2.1 Motion Is Relative

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How can you tell if an object is moving?....Who remembers the answer?

2.1 Motion Is Relative

An object is moving if its position relative to a fixed point is changing.

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• With the people around you, you have 3 minutes to answer # 1-3 on your guided notes…

• We will then popcorn answers

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You can calculate the speed of an object by dividing the distance covered by time.

2.2 Speed

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Before the time of Galileo, people described moving things as simply “slow” or “fast.” Such descriptions were vague.

Galileo is credited as being the first to measure speed by considering the distance covered and the time it takes.

Speed is how fast an object is moving.

2.2 Speed

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Any combination of units for distance and time that are useful and convenient are legitimate for describing speed:

• miles per hour (mi/h)• kilometers per hour (km/h)• centimeters per day• light-years per century

2.2 Speed

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We will primarily use the unit meters per second (m/s) for speed.

If a cheetah covers 50 meters in a time of 2 seconds, what is its speed? TRY IT in the margin of your guided notes…2 minutes…

2.2 Speed

•Let’s check…does m/s make sense if we are solving for SPEED?

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Instantaneous Speed

A car does not always move at the same speed.

You can tell the speed of the car at any instant by looking at the car’s speedometer.

The speed at any instant is called the instantaneous speed.

2.2 Speed

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The speedometer gives readings of instantaneous speed in both mi/h and km/h.

2.2 Speed

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Average speed can be calculated easily ( we will practice this later in class):

For example, a distance of 240 kilometers during a time of 4 hours is an average speed of 60 km/h:

2.2 Speed

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Average Speed

In a trip by car, the car will certainly not travel at the same speed all during the trip. (You speed up, slow down, stop, go etc…)

The driver cares about the average speed for the trip as a whole

The average speed is the total distance covered divided by the time.

2.2 Speed

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If we know average speed and travel time, the distance traveled is easy to find.

2.2 Speed

•So, how can we solve for TOTAL DISTANCE COVERED? Using basic algebra….

•Does anything CANCEL?

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If we know average speed and travel time, the distance traveled is easy to find.

2.2 Speed

So, if your average speed is 80 kilometers per hour on a 4-hour trip, then you cover a total distance of _________________?TRY IT! (on looseleaf, or in the margin of Ch. 2 Guided Notes…work with the people around you, 1 minute!)

x

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2.2 Speed

x

So, if your average speed is 80 kilometers per hour on a 4-hour trip, then you cover a total distance of _________?

4 h x 80 km

h=

4 x 80 km =

1

320 km

•Does anything CANCEL?•So we are left with…

•Let’s check…does km make sense if we are solving for DISTANCE?

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Closing

• Take BACK your do now Pre Assessment

• Now that you have LEARNED how to correctly do this…– Review

– FIX any errors in a different color so I can see your thought process

– Turn back in as your exit slip– Have a great day