Standard 8.1

The velocity of an object is the rate of change of its position

Motion

Anticipatory SetHow does a flying Bird know it is moving?It sees objects on the ground that it passesWhen watching a football game, how do you know the distance of a pass?You see it move past the field markersIf you were on a cruise ship how can you tell the boat is moving forward?You can look for coastal land, or by the stars in the sky

Standard 8.1 (a-c)• A. Know that position is defined in relation to

some choice of standard reference point and a set of reference directions.

• B. Students know that average speed is the total distance traveled divided by the total time elapsed and that the speed of an object along the path traveled can vary.

• C. Students know how to solve problems involving distance, time, and average speed.

LANGUAGE OF THE DISCIPLINEPosition: an objects place or location relative to a reference pointReference point: a marker that is used to determine if something is in motionMotion: the change in an objects position relative to a reference pointSpeed: the measure of how far something moved in a given period of timeAverage speed: how fast something moves over a given period of time

Motion• An object is in motion if it changes position

relative to a reference point.

• To see if in motion:– Pick a STATIONARY reference point– Indicate your position by + or –

• Left/right• Up/down• Front/behind

Position• How can you describe the position?

• You use a reference Point to establish position.Position is when something is stationary

Relative Motion• Relative motion

– depending on what your reference point it things may or may not “be in motion”

(see plane, skydivers, and ground)

Motion Example• You and your classmate are riding the bus to school. Your

classmate is 5 rows ahead of you. You look at the window and see a tree move past. You look across the aisle and see the seats are not moving.

• Is the bus moving?– yes

• Are you moving inside the bus?– no

• Is your classmate moving faster than you (since they are sitting further up)?– No, neither of you are moving inside the bus

Distance vs. Displacement• Distance is the total

length of the actual path between two points (yellow path)

• Displacement is the length and direction of a STRAIGHT line between the starting and ending points (red line)

SPEED• Speed is also known as RATE• Speed Equation

• Average Speed– Most objects vary in speed as they move, so we

need to find the average speed– Equation:

Calculating SpeedIf a distance runner runs 10 miles in one

hour, what is her speed.

Speed = Distance

Time

Speed = 10 miles = 10 mph (miles per hour)

1 hour

Calculating AVERAGE SpeedA cyclist travels 20 kilometers during the first 2

hours. Then he travels 16 kilometers during the next hour. What is his average speed?

Average Speed = Total Distance

Total Time

v= 20 km + 16km = 36 km

2 h + 1 h = 3 h

v= 12 km/h

Calculating SpeedA skateboard rolls down a ramp at

constant speed of 12 m/s. How many meters will the board travel in 4 seconds?

Speed = 12 meters 1 second X 4 seconds

Distance after 4 seconds= 48 Meters

Graphing Speed• What is

happening to the speed/ motion at the blue arrow?

Check for Understanding• What do you need to determine if something

is in motion?

–A reference point

• What is the speed equation?

Practice & HW• Guided Practice:

– Read through Guided instruction on page 23-24 and highlight important information

– Complete the Guided questions in Measuring up on page 23-24

– Raise hand for a stamp• Independent Practice:

– Complete questions 1-4 on page 24• HW:

– complete questions 1-3 on page 25.

Anticipatory Set

How can we make this balloon move along the string?

Standard 8.1 (d-e)D:Students know the velocity of an object must be described by specifying both the direction and the speed of the object.

E:Students know changes in velocity may be due to changes in speed, direction, or both.

LANGUAGE OF THE DISCIPLINEVelocity: speed and direction of an objectVector Quantity: a scientific quantity that contains a magnitude and directionAcceleration: the rate at which velocity changes over time Deceleration: negative acceleration, slowing down

velocity• Remember it is: SPEED + DIRECTION

– Example: the car is going 35 mph southeast

• Changes in velocity may be due to changes in SPEED, DIRECTION, or BOTH.

velocity• Remember it is: SPEED + DIRECTION

• WHAT KIND OF JOBS WOULD KNOWING VELOCITY BE IMPORTANT?– Air Traffic Controller

• If something is moving at a constant speed around a track is it changing velocity?– Yes, because it is changing direction

acceleration• does not just mean “speed up”

• In science, acceleration refers to increasing speed , decreasing speed , or changing direction .

• Sometimes we call decreasing speed, DECELERATION

Calculate acceleration

• Acceleration= Final Velocity - Initial Velocity Time

Practice ProblemAlgernon was running a maze. He must run 20 cm forward, 10 cm to the left, and 30 cm forward. Algernon moves at about 90 cm per minute. How many seconds will it take for him to complete course?• Add up total distance: 20+10+30 = 60 cm• Set up problem 60 cm = 90 cm X 60 secs (1 min)• Cross multiply to solve for X

– 60 (60) = 90 X– 3600/ 90= 40– X= 40 seconds

Check for Understanding• Do the following scenarios represent speed

and/or acceleration?Motion Speed? Velocity?

A car completes one lap at a car races at 185 mph

Geese flying south at 25 mph

Students leaving school at 3:45

A baseball travels at an angle of 45 degrees southwest at 65 mph

Practice & HW• Guided Practice:

– Read through Guided instruction on page 27-28 and highlight important information

– Complete the Guided questions in Measuring up on page 27-28

– Raise hand for a stamp• Independent Practice:

– Complete questions 1-4 on page 28• HW:

– complete questions 1-3 on page 29 (and anything else not finished).

Anticipatory SetWith your arms:What direction does the Y-axis go? What direction does the X-axis go?

Standard 8.1 (f)

F. Students know how to interpret graphs of position versus time and graphs of speed versus time for motion in a single direction.

LANGUAGE OF THE DISCIPLINESlope: in a linear function it shows the rate of change (such as speed or position) over timeLinear: changes over time by a constant amountNonlinear: changes over time by differing amountsOrigin: (0,0), where the x-axis and y-axis meetZero point: where the value of Y equals 0

Graphing• Time is always on the x-axis

• It is “independent” of the speed or distance

• Speed or distance is always on the y-axis

• It is “dependent” on the time

Position Graph• Shows an object’s position over time• Graph:

– Y axis: distance– X axis: time

• What can you tell about the positionBy the graph?

Types of Lines• (insert picture)

Zero Points• Zero Points: when Y value is 0 on a position

graph• All movement away from starting point is (+)

and all movement coming back is (-)

Moving away (+)

Moving back (-)

Zero Points• Zero points are

relative to what you set as the base location/position

• Example: • You might track a

basketball players position on the court. You set their basket as zero position OR… you might set zero point as half court line

basket Half court

Speed Graph• Used to show changes in speed over time

– A flat line does not indicate NO movement- it indicates CONSTANT movement

• What can you tell me about the speed of this bus?

Check for Understanding• What is happening in this graph

dist

ance

Spee

d

Practice & HW• Guided Practice:

– Complete Practice Worksheet• Raise hand for a stamp

• Independent Practice: – Read through Guided instruction on page 31-33 and highlight

important information– Complete the Guided questions in Measuring up on page 31-

33• HW:

– complete questions on page 34 and 35 (and anything else not finished).