Items to pick-up: Admit Ticket/Exit Ticket (3) Cornell Note Sheets

Homework Due Friday, August 5th

COMPOSITION NOTEBOOK CHECK (Journal Entries will begin next week)

Admit Ticket

W h a t i s t h e d i f f e re n c e between Mass and Weight? Wr i t e yo u r a n s w e r i n a complete sentence.

Physics Pre-Test

Quietly Take Test

Keep eyes on your own paper

Do your best!

PHYSICS VOCABULARY

Physics Vocabulary

Scientific Method

Inertia

Velocity

Gravity

Mass

Weight

Density

SCIENTIFIC METHOD

The practice of science that typically incorporates the following steps: Observe, Question, Hypothesize, Predict, Test Predictions and Draw a Conclusion.

INERTIAThe resistance of any physical object to any change in its state of motion (this includes changes to its speed, direction or state of rest). It is the tendency of objects to keep moving in a straight line at constant velocity.

VELOCITYThe velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of its speed and direction of motion (e.g. 60 km/h to the north).

GRAVITYThe force that attracts a body toward the center of the earth, or toward any other physical body having mass. For most purposes Newton's laws of gravity apply, with minor modifications to take the general theory of relativity into account. It is one of the four fundamental forces (interactions) in nature.

THE HISTORY OF GRAVITY

Sir Isaac Newtontheorized the

Law of Gravitation in 1687

UNIVERSAL LAW OF GRAVITATION

Gravity is greater when mass is larger and distance is shorter. It can be measured in Newtons (1 Newton= weight of one apple)

Forcemeters.

Mass and Weight are two different Properties of Matter

MASS ❖ Mass is a physical property of

matter that explains how much matter is in an object

❖ Mass does not change when gravity changes

WEIGHT ❖ Weight is a force which is

calculated by multiplying the acceleration of gravity times

mass. ❖ Weight can change when

gravity changes

MASSThe quantity of matter in an object. It is also the measure of the inertia or sluggishness that an object exhibits in response to any effort to start it, stop it, or change its state of motion in any way. Mass is measured in kilograms (kg).

WEIGHTThe force on an object

due to gravity.

DENSITYThe measure of how much mass is squeezed into a given space; it is the amount of matter per unit volume:

Density = _Mass_ Volume

Exit Ticket

Based on today’s lesson, what did you learn about Mass, Weight and Gravity? Write a paragraph using complete sentences (use the back of the page if needed).

Motion

The Need for Speed

What is motion?

• You are probably thinking that motion is when something is moving…

• Unfortunately, that definition won’t do us much good.

• How do we know something is moving? • How do we measure it? • How do we tell fast motion from slow

motion?

Well…• An object is in motion when its distance from

another object is changing.

• We can tell something is moving when we can measure it!

• Motion is described relative to something else. We call this place or object used for comparisons to determine if something is in motion a reference point. – For example, even though you are in your seat, you

are moving 30k/s relative to the sun!

How do we measure motion?

• We measure motion based on how fast it is occurring, or better put, the rate at which it occurs.

•Rate tells us the amount of something that occurs or changes in one unit of time.

• You are probably more familiar with this concept when referring to speed.

The Need for Speed!

• Speed is one type of rate.

• The speed of an object is the distance the object travels per unit of time.

• Lets think of driving. Most streets in Phoenix are 45 miles per hour. So, if I drive the rate of 45 miles per hour, then I will travel 45 miles in one hour!

How do I calculate speed?

• Speed=Distance Time

S=D TOR

A cheetah can maintain a constant speed of 25m/s. At this rate, how far will it travel in 10 s?

• Remember the steps of problem solving!

• 1. Write the equation & rearrange. S=D/T or D=ST 2. Write the knowns S=25m/s D= ? T= 10s

3. Convert – We don’t need to

4. Plug! D=(25m/s) x (10s)

5. Chug! D=(25m/s) x (10s) =250m

6. Box Answer!

Velocity

• Society uses the terms “speed” and “velocity” interchangeably.

• But…they are wrong.

•Velocity is speed with a given direction

• So, speed is going 30m/h

• Velocity is going North 30m/h

“We’re not in Kansas anymore…

• If we lived in Kansas during Tornado season, it really wouldn’t do us much good to know the speed of a storm traveling with a tornado brewing inside it.

• But… • It would be very beneficial to know the

speed of a tornado, and the direction, especially if it is headed toward our house.

The Rubber Hits the Road…

• Speed is distance over time

• Example: 65 m/h

• Velocity is speed and direction

• Example: 65 m/h South

Motion

Acceleration

Acceleration

• Consider a car stopped at a stoplight. As the light turns green, the driver presses the gas pedal and gradually increases speed, or accelerates.

• Acceleration is the rate at which velocity changes.

• Remember, velocity is speed and direction.

Velocity change

• Velocity can either increase or decrease

• The direction can also change

• Acceleration involves a change in either of these components.

• Acceleration refers to increasing or decreasing speed and changing direction.

Increasing Speed

• When an object increases speed, it experiences acceleration.

• When a football is thrown, it accelerates.

• When a pitcher throws a ball, it accelerates.

• When a horse begins to run, it accelerates.

Decreasing Speed

• Objects that speed up, eventually slow down.

• A ball that is thrown eventually rolls to a stop.

• A car slows down as the driver steps on the brake.

• A runner finishing a race, eventually stops.

Changing Direction

• Acceleration is change in speed or direction.

• A car accelerates as it makes a turn.

• A Ferris Wheel at the fair is accelerating (direction is always changing)

• The Earth rotating around the sun.

Calculating Acceleration

• To determine the acceleration of an object, you must calculate the change in velocity during each unit of time.

Final Velocity - Initial Velocity Acceleration= Time

How else can we simplify the equation?

• We can summarize the acceleration equation by the following:

Vf - Vi A= t

Units

• If velocity is measured meters/second

• And time is measured in seconds,

• Then, acceleration is measured in meters per second per second.

• Acceleration units are m/s2

An Example:

• A roller coaster car rapidly picks up speed as it rolls down a slope. As it starts down the slope, its speed is 4 m/s. But 3 seconds later, at the bottom of the slope, its speed is 22m/s. What is its average acceleration?

• Relax! This is easy, just follow the steps for solving word problems!

Just follow the steps!

Step 1: Write the equation Vf – Vi A= t

A roller coaster car rapidly picks up speed as it rolls down a slope. As it starts down the slope, its speed is 4 m/s. But 3 seconds later, at the bottom of the slope, its speed is 22m/s. What is its average acceleration?

Step 2: Write the knowns:

A=?

t= 3 s

Vf=22 m/s

Vi=4 m/s

Step 3: Convert

-Not needed

Step 4: Plug!

22 m/s – 4 m/s

A=

3s

Step 5: Chug! 18m/s

A= = 6 m/s2

3s

Step 6: Box Answer!

SpeedMeasuring motion

Calculating Speed

○ Speed (S) = distance traveled (d) / the amount of time it took (t).

S = d/t

Units for speed

○ Depends, but will always be a distance unit / a time unit

● Ex. Cars: mi./h ● Jets: km/h ● Snails: cm/s ● Falling objects: m/s

Calculating speed

○ If I travel 100 kilometer in one hour then I have a speed of…

○ 100 km/h

○ If I travel 1 meter in 1 second then I have a speed of….

○ 1 m/s

S = d/t

Question

○ I travelled 25 km in 10 minutes. What is my speed? ● A) 25000 km/min ● B) 250 km/min ● C) .025 km/min ● D) 2.5 km/min

Average speed

○ Speed is usually NOT CONSTANT ● Ex. Cars stop and go regularly ● Runners go slower uphill than downhill

○ Average speed = total distance traveled/total time it took.

Calculating Average Speed

○ It took me 1 hour to go 40 km on the highway. Then it took me 2 more hours to go 20 km using the streets.

○ Total Distance: ● 40 km + 20 km = 60 km

○ Total Time: ● 1 h + 2 h = 3 hr

○ Avg. Speed: ● total d/total t = 60 km/3 h = 20 km/h

Question○ I ran 1000 m in 3 minutes. Then ran

another 1000 m uphill in 7 minutes. What is my average speed? ● A) 100 m/min ● B) 2000 m/min ● C) 10 m/min ● D) 200 m/min ● E) 20 m/min

Total Dist. = 1000 m + 1000 m = 2000 m

Total Time = 3 min + 7 min = 10 min

Avg speed = total dist/total time =

2000m/10 min = 200 m/min = D

Graphing Speed: Distance vs. Time Graphs

Distance(Km)

0

350

700

1050

1400

Time(hr)

1 2 3 4 5 6 7

Phoenix

Denver

Graphing Speed: Distance vs. Time Graphs

Distance(km)

0

350

700

1050

1400

Time(hr)

1 2 3 4 5 6 7

Run

Graphing Speed: Distance vs. Time Graphs

Distance(km)

0

350

700

1050

1400

Time(hr)

1 2 3 4 5 6 7

Run=?3 h

600 km

Graphing Speed: Distance vs. Time Graphs

Distance(km)

0

350

700

1050

1400

Time(hr)

1 2 3 4 5 6 7

Run=?3 minutes

600 m

Different SlopesD

ista

nce

(km

)

0

2

4

5

7

Time (hr)1 2 3 4 5 6 7

Run = 1 hr

Run = 1 hr

Run = 1 hr

Rise = 0 km

Rise = 2 km

Rise = 1 km

Slope = Rise/Run = 1 km/1 hr = 1 km/hr

Slope = Rise/Run = 0 km/1 hr = 0 km/hr

Slope = Rise/Run = 2 km/1 hr = 2 km/hr

Question

○ Below is a distance vs. time graph of my position during a race. What was my AVERAGE speed for the entire race?

Dis

tanc

e (k

m)

0

3

6

9

12

Time (hr)0 1 2 3 4 5 6

Average Speed = Total distance/Total time = 12 km/6 hr = 2 km/hr

Run = 6 hr

Rise = 12 km

Question

○ What does the slope of a distance vs. time graph show you about the motion of an object?

○ It tells you the SPEED

Question

○ Below is a distance vs. time graph for 3 runners. Who is the fastest?

Dis

tanc

e (m

i.)

0

2

3

5

6

Time (h)0 1 2 3 4 5 6

Bob JaneLeroy

Leroy is the fastest. He completed the race in 3 hours

Homework Due

“CALCULATING SPEED” WORKSHEET DUE TOMORROW COMPOSITION NOTEBOOK CHECK DUE FRIDAY, 8/5/16 (Journal Entries will begin next week)