MOTION A review

Key Concepts What is motion? What is speed? How do you calculate speed? What is the difference between speed and velocity? How can speed be graphed?

What is motion? When an object changes position over time when compared with a reference point

Reference Point The object that stays in place to compare motion What is the reference point in the picture?

1 km North 1.Sandy needs to run errands. She walks 5 km north to return some movies. She keeps going north 3 km to buy groceries. She walks back south to her house. After 7 km she decides to stop at Starbucks. Where is she from her house?

21 km North 2. Jose drives 20 km north to downtown after dinner he walks 1 km south to the ballpark. After the game he walks 2 km north to his friend’s house. Where is he compared to his house?

What is speed? The rate at which an object moves. It depends on the distance traveled and the time taken to travel that distance.

Average Speed Average Speed = Total distance Total Time Example: 360km = 90km 4hrs. Hr.

3. A plane traveled 600 km in 2 hours. How fast was it traveling? 300 km/hr

4. Juan kicked a soccer ball 35m down field 4. Juan kicked a soccer ball 35m down field. The ball had a speed of 10m/s. How long did it take to get there? 3.5s

4 hours 5. Julieta walked 20 km at 5 km/hr. How long did it take her to finish the race?

What is the difference between speed and velocity?

Velocity is Speed with direction

What are some units for velocity? 600 km/min North 8 m/s south 65 mph west

When does velocity change? Velocity changes as Speed or Direction changes

Changes in Velocity: or slower Velocity changes when speed goes faster Velocity changes when direction changes 2m/sec up to 2m/sec down You can’t move in a circle and keep the same velocity

Sample Problem 6 Juan is walking 2 m/s South on a train that is moving 60 m/s North. What is his velocity? 60-2 = 58m/s north

Sample problem 7 Jessica walks 3 m/s west to the front of a bus moving 30m/s west. What is her velocity? 30 + 3= 33 m/s west

How can speed be graphed? 2 ways 1. On a distance vs. time graph 2. On a speed vs. time graph

What is the MOST important thing when reading a motion graph? Knowing what kind if graph it is!

Distance vs. time graphs You can read the distance directly

8. How far is the car moving between seconds 40 and 60? 0m/s

Distance vs. time graphs You can calculate the speed Slope=speed

9. What is the speed of the object? 50/5= 10 m/s

Speed vs. time graphs You can read the speed

What is happening to the speed? increasing

10. What is the speed between 3 and 7? 2km/min

You can calculate the acceleration Slope=acceleration Speed vs. time graph You can calculate the acceleration Slope=acceleration