One Dimensional Motion Speed and Velocity

Learning Objectives TLW know concepts of force and motion evident in everyday life (TEKS 4) TLW describe and calculate an object’s motion in terms of position, displacement, speed and acceleration (TEKS 4.A) TLW measure and graph distance and speed as a function of time using toys (TEKS 4.B) TLW investigate how an object’s motion change only when a net force is applied using toy cars, vehicle restraints, sports activities and classroom objects (TEKS 4.C)

Anticipatory Activity Audience Participation – Get Your Move On… Grooving to the Oldies

I. What is Motion A. Motion – an object has moved 1. change in position of an object 2. compared to the background that is not moving 3. frame of reference – background used for comparing motion

4. most common frame of reference – the Earth 5. Everything in the universe moves

B. Motion can be measured 1. Speed is the easiest way to measure motion a. position – location of object in reference to an origin b. displacement – change in position c. distance – how far an object moves in total d. time – how long it takes an object to move e. speed – how fast an object moves

2. Formula for measuring motion: Speed = distance ÷ time or s = d / t a. this is used to calculate average speed b. Ex. A racecar finishes a 500 mile race in 3.5 hours. What is the average speed? s = d / t s = 500 mi / 3.5 hr s = 142.86 mi / hr

Drive 100 mi / hr for 3 hours how far? d = vt d = 100mi / hr * 3hr c. Finding distance: Drive 100 mi / hr for 3 hours how far? d = vt d = 100mi / hr * 3hr d = 300 mi

d. Finding time: If you are traveling at 60 mph, how long will it take you to get to Austin (120 miles away)? how long? t = d / v t = 120 miles / 60 miles per hr t = 2 hours

a. distance = meters or kilometers 3. Units of measure a. distance = meters or kilometers b. time = seconds or hours c. speed = meters per second (m/s) or miles per hour (mi/hr)

C. Velocity 1. motion also includes direction 2. Velocity is the speed AND direction of an object’s motion 3. Velocity is also measured as negative or positive a. object moving in one direction has a positive velocity

b. an object moving in the opposite direction has a negative velocity c. Ex. A rocket traveling up has a positive velocity and as it falls back down it has a negative velocity Negative does NOT mean slower

4. Velocity of an object changes if. an object changes speed or 4. Velocity of an object changes if an object changes speed or direction ***a car driving in a straight line at a constant speed does not have a change in velocity***

5. Use this formula for velocity v = d / t BUT you must add direction = up, down, east, west, etc. Ex. A bird flies 200 meters to the west in 100 seconds, what is the velocity? v = 200 m / 100 s v = 2 m / s to the west

The Magic Triangle d v t

Group Practice

Using Graphs to Determine Displacement and Velocity y = mx + b

How many meters can Swimmer 1 cover in 30 sec? How far will Swimmer 2 go in 30 sec? Predict the number of m Swimmer 1 can go in 60 sec Predict the number of m Swimmer 2 can go in 60 sec. Which swimmer has the greatest speed? Calculate the speed of Swimmer 1 Calculate the speed of Swimmer 2

http://www. sidebysidetutoring http://www.sidebysidetutoring.com/blogs/wp-content/uploads/2010/09/x-vs-t.jpg

Interpreting the Graph How far did you travel in the first 2 seconds? from 4 m to 6 m -- or 2 m What was your direction? up or forward or __________ Calculate your speed & velocity v = distance traveled 2 m = 1 m/s forward time 2 s

D. Calculations Ex. 1 What is the average speed of a bicycle that traveled 15 m in 30 seconds? Know: d = 15 m t = 30 sec s = ? s = d / t s = d / t s = 15 m / 30 s s = .5 m / s

Ex. 2 A hot air balloon was traveling an average of 2 mi / hr. It traveled for 32 hours. How far did it travel? Know: v = 2 mi / hr t = 32 hours d = ? v = d / t Use “magic triangle” d = vt 2 mi / h * 32 hrs d = 64 mi d v t

Ex. 3 A snail crawling 0.005 m / s, traveled a record breaking 1m. How long did it take the snail to break the record? Know: v = 0.006 m / s d = 1 m t = ? v = d / t use “magic” triangle t = d / v t = 1m / 0.006m/s t = 200 s d v t

Ex. 4 How much time do you have to escape from an elephant charging straight towards you 15 meters away and running 3 meters per second? Know: d = 15 m v = 3 m / s straight t =? v = d / t t = d / v t = 15 m/ 3 m / s t = 5 sec

Ex. 5 What is the velocity of a boat traveling north 23 meters in 15 seconds? know: d = 23 m t = 15 s v = ? v = d / t v = d / t v = 23 m / 15 s v = 1.5 m / s north

Independent Practice Motion Calculations – Practice Set 1

Labs One or more of the following labs will be performed from IPC Manual or other source Physics 500 (Teaching Physics for 1st Time p. 59) Graphing Student Motion I (Teaching Physics for 1st Time p. 61) Hot Wheelin’ (link) What is speed and how is it measured? (IPC Manual - p. 8 & 9) Can you predict the speed of the car at any point on the ramp? (IPC Manual - p. 10 & 11) How do you model motion of the car? (IPC Manual - p. 12 & 13) Periodic Groups will Read lab procedures together Set up labs according to scientific method Identify potential hazards, precautions, and PPE (if needed)