Speed, Velocity, and Acceleration Motion in Motion Speed, Velocity, and Acceleration

Standard Check Today’s Standard(s): S8P3. Students will investigate relationship between force, mass, and the motion of objects.   a. Determine the relationship between velocity and acceleration.

Catalyst   “How fast is that car going?” is an imprecise question that has two scientific answers. You could respond with the car’s speed or the car’s velocity. What’s the difference between speed and velocity? See if you can find out by watching this music video “Speed and Velocity” by They Might Be Giants. (URL: http://vimeo.com/5395097) 1. What’s the difference between speed and velocity? 2. What units could we use to measure how fast something is moving?

**Velocity is a VECTOR because it REQUIRES a DIRECTION!!!** Formula Formula for speed (and velocity): Speed = Distance ÷ Time **Velocity is a VECTOR because it REQUIRES a DIRECTION!!!**

Units for Speed and Velocity Units for Speed: km/hr (kilometers per hour); m/s (meters per second) Units for Velocity: km/hour SOUTH; m/s EAST *Speed is a SCALAR, which means it does NOT require a direction!*

VIDEO TIME! (Have you heard that terrible singer guy?  His video is online at: https://www.youtube.com/watch?v=Tzdw0aEgimw  . Don’t ask me why anyone would ever choose to listen to it.)

Catalyst Part 2: What does “miles per hour” really mean Catalyst Part 2: What does “miles per hour” really mean? CALCULATORS AT THE READY! What does it mean if a person is crawling 1 kilometer per hour (1 km/h)? In one hour… In one minute…

MORE APPLICATION What does it mean if a car is moving at 60 kilometers per hour (60 km/h)? In one hour… In one minute…

A LITTLE MORE… What does it mean if the Earth’s plates are drifting at 2 centimeters per year (2 cm/year)? In one year… In one decade (____ years)… In one century (_____ years)…

LET’S CALCULATE… How fast does Usain Bolt run? Watch the video to find out: https://www.youtube.com/watch?v=2O7K-8G2nwU How about Para-Olympian Jason Smyth? Watch the video to find out: https://www.youtube.com/watch?v=LZovT5yZJdQ

WHAT ARE YOUR ANSWERS?? Usain Bolt??? Jason Smyth??

Speed Facts about SPEED… Examples: 10 m/s; 100 km/hr Scalar! (No Direction) The distance traveled by an object divided by the time taken to travel that distance. S = D ÷ T

Velocity Facts about Velocity… Speed with DIRECTION! Vector! Can combine and take the difference between velocities to determine final velocity. Examples: 10 m/s EAST; 100 km/hr SOUTH

CIRCLE the SPEEDS… You should have circled… 50 m/s 12 mm/year 175 mm/s 2 cm/year How’d ya do??

VELOCITY!!! She may be coming YOUR direction!! AHHHHH!!!! Discussion Question #1 The police are tracking an escaped prisoner. Would it be more helpful to know her speed or her velocity? WHY? VELOCITY!!! She may be coming YOUR direction!! AHHHHH!!!!

Discussion Question #2 SPEED! DUH!!! Your parents don’t trust your older brother with his car. They install a device into the car to text them whenever he goes faster than 70 miles per hour. Does this device need to monitor his speed or his velocity? WHY? SPEED! DUH!!!

VELOCITY!!! Are YOU in the path??!! Discussion Question #3 Think of an example in your life where you care how fast something is moving (a bus, a bike, a roller coaster, etc). Do you really care about the object’s speed or its velocity? WHY? VELOCITY!!! Are YOU in the path??!!

A What is Acceleration?? During part I, the object is: A. Accelerating Catalyst During part I, the object is: A. Accelerating B. Decelerating C. Neither. Explain how you know: A

C What is Acceleration?? During part II, the object is: Catalyst During part II, the object is: A. Accelerating B. Decelerating C. Neither. Explain how you know: C

B What is Acceleration?? During part III, the object is: Catalyst During part III, the object is: A. Accelerating B. Decelerating C. Neither. Explain how you know: B

VIDEO TIME Moving On: Check out this video on acceleration: http://www.youtube.com/watch ?v=e5Gl2LLLAGo

So…What IS Acceleration? When people are reviewing sports cars, they often talk about the time it takes the car to go “0-60.” What does that mean? In scientific terms, “0-60” time is just a measure of the car’s ACCELERATION!!! They are timing how long it takes the car’s speed to increase from 0 miles per hour (mph) to 60 mph.

VOCABULARY CHECK! Acceleration is how quickly an object changes its VELOCITY (SPEED OR DIRECTION)! DECELERATION is how quickly an object is decreasing its speed.

Acceleration UNITS… To CALCULATE Acceleration, use the formula: a = acceleration ∆ = “change in” Acceleration is measured in meters per second per second since it is a measure of change over time. It is classically written m/s2, but may be said: “meters per second per second” OR “meters per second squared.”

Use the triangle to solve for ANY variable! YOU CAN SOLVE IT ALL!!! Use the triangle to solve for ANY variable! D = DISTANCE D R = RATE (VELOCITY) T = TIME R T SO… D = R X T R = D ÷ T T = D ÷ R

WHICH ONE?? Which of the following describes acceleration? 10 cm 10 cm/second 10cm/second/minute 10 cm/second/second

Speeding up, changing direction Constant speed in ONE direction! EXAMPLES: Some examples of acceleration: Some examples of deceleration: Some non-examples of acceleration: Speeding up, changing direction Slowing down Constant speed in ONE direction!

WRAPPING IT UP!!! When you CHANGE DIRECTIONS you are actually accelerating! This is because acceleration happens whenever your VELOCITY changes.

EXIT TICKET!!!! DUE TOMORROW!!