Do NowIn your notebook: Imagine a car that is moving at a constant speed of 4 m/s. Unfortunately, the car is leaking oil. One drop of oil falls onto the road every 1 second. Draw a picture of what the pattern of drops will look like on the road after 5 seconds pass.

Enduring Understanding: A small number of known values and a basic understanding of the patterns involved in motion may reveal a wide variety of kinematic information.

Enduring Understanding: The study and application of kinematic information has affected society.

Essential Question: How may we symbolically represent kinematic information? What may be gained by doing this?

Essential Question: How do units of measurement affect kinematic understanding?

Essential Question: How has the study of kinematic information affected society?

Essential Question: Why didn’t people regularly study and use kinematic information prior to the 17th century?

AccelerationIn your own words, what is acceleration?Acceleration: The rate of change for speed or velocity.

Symbolically;

a = Δv t

Visualizing Acceleration

A car is accelerating at a rate of 3m/s2.

0 s 1 s 2 s 3 s 4 s

0 m/s m/s m/s m/s m/s

An object starts at rest. After 10 s, it has a speed of 50 m/s. What was its acceleration?

Vi = 0 m/s Vi is the initial speedVf = 50 m/s Vf is the final speed

t = 10 s a = (vf - vi )/t_______________________________ (50 m/s – 0 m/s)a = ------------------------ = 5

10s

What is the unit?

m/s2

a = (vf – vi ) tRearrange this formula to solve for vf

vf =

vi + at

This is the symbolic representation of our second kinematic equation.

An object has an acceleration of 12 m/s2. If the object starts at rest, what is its speed after 5 s?

a = 12 m/s2

t = 5 svi = 0 m/svf = ?

vf = vi + at

0 m 12 m 5 svf = ----- + ------- x s s2

vf = 60 m/s

How far did the object travel during that time period?

Average speed = (vi + vf ) 2

d = vt

Average speed = (0 m/s + 60 m/s) / 2

Average speed = 30 m/s

d = (30 m/s)(5 s) = 150 m

Note:this only works for a constant acceleration