DISTANCEVS.

DISPLACEMENT

• Distance: magnitude of length for the path traveled. (follow Billy)

I. Distance

II. Displacement

• Displacement: Change in position, ∆ x• ∆ : Greek letter Delta

: means “Change in…”• x : position

II. Displacement

Initial Position

Final Position

• ∆ x = xf – xi

xf : x final

xi : x initial

• Displacement is a vector.

II. Displacement

• Vector: has direction and magnitudeex: 50 meters West

• Scalar: has magnitude, but no directionex: 65 miles per hour

III. Vector and Scalar

AVERAGE SPEEDVS.

AVERAGE VELOCITY

I. Average Speed

• Average Speed = Total distance Total time

• Average Speed: the total distance traveled divided by the total time it takes to travel that distance

• v = ∆x / ∆t

• v : bar v, average velocity

• Average Velocity: the displacement divided by the time taken

II. Average Velocity

Which value is greater for Billy… the average speed or the average velocity?

Talk to your neighbor…

average speed =

TOTAL DISTANCE / total time

average velocity = displacement / total time

• average speed ≥ average velocity

• When is the average speed = average velocity?

III. Average Speed vs. Average Velocity

Discuss!

• When is the average speed = average velocity?

… when distance = displacement… a straight line!

III. Average Speed vs. Average Velocity