Items to pick-up: Admit Ticket/Exit Ticket (3) Cornell Note Sheets
DUE TODAY!!! COMPOSITION NOTEBOOK CHECK (Journal Entries will begin next week)
MONDAY AUGUST 8, 2016 All Periods will meet in Lab 2
Admit Ticket W h a t i s t h e d i f f e re n c e between Speed and Velocity? Wr i t e yo u r a n s w e r i n a complete sentence.
Exit Ticket Based on today s lesson, fill in the blanks with the correct answer. refers to increasing or decreasing speed and changing direction. is an international unit for measuring distance. is the speed and direction of an object.
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 OR S=D T
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. Acceleration= Final Velocity - Initial Velocity Time
How else can we simplify the equation? We can summarize the acceleration equation by the following: A= Vf - Vi 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 A= Vf Vi 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 Step 6: Box Answer! A= = 6 m/s2 3s
Speed Measuring motion
Measuring Distance Meter international unit for measuring distance. 1 mm = 50 m
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 S = d/t 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
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 Total Dist. = 1000 m + 1000 m = 2000 m D) 200 m/min E) 20 m/min 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 1400 Denver 1050 Distance (Km) 700 350 0 Phoenix 1 2 3 4 5 6 7 Time (hr)
Graphing Speed: Distance vs. Time Graphs 1400 1050 Distance (km) 700 350 Run 0 1 2 3 4 5 6 7 Time (hr)
Graphing Speed: Distance vs. Time Graphs 1400 1050 Distance (km) 700 350 Run=? 3 h 600 km 0 1 2 3 4 5 6 7 Time (hr)
Graphing Speed: Distance vs. Time Graphs 1400 1050 Distance (km) 700 350 Run=? 3 minutes 600 m 0 1 2 3 4 5 6 7 Time (hr)
Different Slopes 7 Distance (km) 5 4 2 0 Slope = Rise/Run = 1 km/1 hr = 1 km/hr Run = 1 hr Slope = Rise/Run = 0 km/1 hr = 0 km/hr Rise = 1 km Run = 1 hr Rise = 0 km 1 2 3 4 5 6 7 Time (hr) Run = 1 hr Rise = 2 km Slope = Rise/Run = 2 km/1 hr = 2 km/hr
Question Average Speed Below = is Total a distance distance/total vs. time time graph = of 12 my km/6 hr position during = 2 a km/hr race. What was my AVERAGE speed for the entire race? 12 Distance (km) 9 6 3 Rise = 12 km 0 0 1 2 3 4 5 6 Time (hr) Run = 6 hr
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? 6 Distance (mi.) 5 3 2 Bob Leroy Jane 0 0 1 2 3 4 5 6 Time (h) Leroy is the fastest. He completed the race in 3 hours
Acceleration Acceleration = speeding up Acceleration the rate at which velocity changes Can be an: Increase in speed Decrease in speed Change in direction
Types of acceleration Increasing speed Example: Car speeds up at green light Decreasing speed screeeeech Example: Car slows down at stop light Changing Direction Example: Car takes turn (can be at constant speed)
Velocity Velocity the SPEED and DIRECTION of an object. Example: An airplane moving North at 500 mph A missile moving towards you at 200 m/s
Question What is the difference between speed and velocity? Speed is just distance/time. Velocity includes direction as well.
Question How can a car be accelerating if its speed is a constant 65 km/h? If it is changing directions it is accelerating
Calculating Acceleration If an object is moving in a straight line Units of acceleration: m/s 2
Calculating Acceleration 0 s 1 s 2 s 3 s 4 s 0 m/s 4 m/s 8 m/s 12 m/s 16 m/s
Question A skydiver accelerates from 20 m/s to 40 m/s in 2 seconds. What is the skydiver s average acceleration?
Graphing Acceleration Can use 2 kinds of graphs Speed vs. time Distance vs. time
Graphing Acceleration: Speed vs. Time Graphs 12 Speed (m/s) 9 6 3 0 0 1 2 3 4 5 6 Time (s) 1)Speed is increasing with time = accelerating 2)Line is straight = acceleration is constant
Graphing Acceleration: Speed vs. Time Graphs 12 9 Speed (m/s) 6 3 Run = 2 s Rise = 4 m/s 0 0 1 2 3 4 5 6 Time (s) 1)In Speed vs. Time graphs: Acceleration = Rise/Run = 4 m/s 2 s = 2 m/s 2
Graphing Acceleration: Distance vs. Time Graphs 40 Distance (m) 30 20 10 0 0 1 2 3 4 5 Time (s) 1)On Distance vs. Time graphs a curved line means the object is accelerating. 2)Curved line also means your speed is increasing. Remember slope = speed.
Question 12 Speed (m/s) 9 6 3 Run = 3 s Rise = -6 m/s 0 0 1 2 3 4 5 6 Time (s) Above is a graph showing the speed of a car over time. 1) How is the speed of the car changing (speeding up, Slowing down, or staying the same)? 2) What is this car s acceleration? 1) The car is slowing down 2) Acceleration = rise/run = -6m/s 3s = -2 m/s 2
Question: 40 Distance (m) 30 20 10 0 0 1 2 3 4 5 Time (s) The black and red lines represent a objects that are accelerating. Black is going a greater distance each second, so it must be speeding up. Red is going less each second, so must 1)Which line represents an object that is accelerating? Remember: in distance vs. time graphs: be slowing down curved line = accelerating, flat line = constant speed
Question: Hard one 50 12 Distance Speed (m/s) (m) 389 256 133 0 0 1 22 3 3 4 4 5 5 6 6 Time Time (s) (s) Above is a graph showing the speed of a car over time. 1)What would a distance vs. time graph for this look like?
CONSTANT VELOCITY LAB: BUGGY CARS
Team Positions Time Keeper(s) Data Recorder Tape Marker Measurer Car Operator
Purpose Examine the motion of the buggy Measure the position of the buggy with respect to time Create a position vs. time graph for the buggy Develop a mathematical model for the motion of the buggy
Materials Dune buggy Meter Stick Stop Watch Tape (marking device)
Homework Due CALCULATING SPEED WORKSHEET DUE MONDAY, AUGUST 8, 2016
MONDAY AUGUST 8, 2016 All Periods will meet in Lab 2