Warm Up 10-29-12 Convert! 15 inches = _____ cm 360 years = ____ hours  

Motion Definition: When an object changes position Position depends on The Frame of Reference

Frame of Reference Frame of Reference = point of view Motion is a change in position relative to a frame of reference

If you are standing in one place, and your friend walks by you, are you moving relative to your friend? Is your friend moving relative to you? Answer You are moving relative to your friend, and your friend is moving relative to you!

If you and your friend are walking down the hall together at the same speed, in the same direction, are you moving relative to your friend? Is your friend moving relative to you? Are either of you moving relative to the earth?

Answer You are NOT moving relative to your friend, and your friend is NOT moving relative to you. You both are moving relative to the earth.

Speed The distance an object travels per unit of time (Example: m/s) Equation Speed = Distance ÷ Time Instantaneous Speed: speed at one moment

Example Example: A car travels 300km in 6 hours. What is the speed of the car?

Example How far can a plane travel if it flies 800km/hr for 9 hours?

Another Example How long does it take a ship to go 500 km if it travels at a speed of 50km/hr?

Average Speed How quickly an object traveled a specific distance Average speed (m/s) = total distance (m) total time (s)

Example What is the average speed of a car that travels a distance of 750 m in 25 sec?

Velocity The speed and direction of motion Example: a hurricane Objects have different velocities IF: They have different speeds Or The are moving in different directions Velocity changes if: -Speed or direction changes

When would it be important to know velocity instead of speed?

Example What is the velocity of a boat that travels south from St. Peter to Mankato (10 miles) in 15 minutes?