Motion Notes

Title = key ideaBullets = supporting detail or definition

Speed

the rate which something moves

speed = distance time➗

s = d / t

units = meters / secondExample:If Billy jogs 10 meters in 5 seconds, what is his average speed?

10 meters 5 seconds = 10m/5s = 2 ➗m/s

Velocity

the rate which something moves in a specific direction

velocity = displacement time➗

v = d / t

units = meters / secondExample:If Bonnie jogs north 20 meters in 5 seconds, what is his average velocity?

20 meters 5 seconds = 20m/5s = 4 m/s north➗

Velocity

Velocity

vector quantity = direction matters

displacement = change in position

Example:Sanchez smacks a home run into the outfield. He runs around all bases, a total of about 110 m. It takes him 20 seconds to reach home plate.

a. Calculate Sanchez’s average speedb. Calculate Sanchez’s average velocity

Example:Sanchez smacks a home run into the outfield. He runs around all bases, a total of about 110 m. It takes him 20 seconds to reach home plate.

a. Calculate Sanchez’s average speed

Speed = distance / time

Speed = 110 meters / 20 seconds

Speed = 5.5 m/s

Example:Sanchez smacks a home run into the outfield. He runs around all bases, a total of about 110 m. It takes him 20 seconds to reach home plate.

b. Calculate Sanchez’s average velocity

Velocity = displacement / time

Velocity = 0 meters / 20 seconds

Velocity = 0 m/s

Acceleration

the rate at which velocity changes

increase in velocity = positive acceleration

decrease in velocity = negative acceleration

acceleration = change in velocity / time

a = (v2- v1) / t

units = m/s/s or m/s2

Acceleration

a vector quantity, so acceleration changes with...

direction

speed

Example:My dog Bailey is sitting on the patio watching a squirrel. She suddenly starts running at 2 m/s towards the tree. She runs in a straight path towards the tree for 5 seconds. What is her average acceleration?

Acceleration = (v2- v1) / t ● V2 = 2 m/s towards the tree● V1 = 0 m/s facing towards the tree● t = 5 seconds

a = (2 m/s - 0 m/s) / 5 sa = (2 m/s) / 5 sa = 0.4 m/s/s

Is this positive or negative acceleration?

Example:Aubrey is driving to school at 20 m/s. As she enters the school zone she slows to 9 m/s. It takes her 5 seconds to fully slow down. What is her average acceleration during those 5 seconds on this straight road?

Acceleration = (v2- v1) / t ● V2 = 9 m/s straight● V1 = 20 m/s straight● t = 5 seconds

a = (9 m/s - 20 m/s) / 5 sa = (-11 m/s) / 5 sa = -2.2 m/s/s

Is this positive or negative acceleration?

Acceleration

1. If acceleration equals zero, can there be movement occurring? Explain your thinking…

Yes. For example, velocity can be constant at 10 m/s and acceleration won’t change.

Motion Analysis Practice

http://www.physicsclassroom.com/Physics-Interactives/1-D-Kinematics/Name-That-Motion/Name-That-Motion-Interactive