AccelerationMotion Unit

Acceleration objects that speed up, slow down, or change direction

have accelerated

Acceleration = change in velocity

Interval of time

a = v = vf – vi

t tf ti

speeding up is a change in velocity and therefore is considered acceleration

a car traveling around a corner at constant speed also represents acceleration due to the change in direction.

2

Question You are traveling on a bus at 25m/s. In two seconds, the bus accelerates to 30m/s. What is the acceleration?

a = v = 30 m/s - 25 m/s = 5m/s = 2.5 m/s2

t 2s 2s

when speed increases, acceleration is positive.

when speed decreases, acceleration is negative (also known as deceleration)

3

Assignment Acceleration problems (11-3)

Build an accelerometer

Velocity- Time Graphs **** Slope on a velocity- time graph represents

ACCELERATION ***** **** Slope on a velocity- time graph represents

ACCELERATION ***** **** Slope on a velocity- time graph represents

ACCELERATION *****

Uniformly Accelerated Motion

Is an object that increases its speed at a constant rate

This represents an object accelerating uniformly.

6

Velocity vs. Time

0

5

10

15

20

25

30

35

40

0 1 2 3 4 5Time (s)

Vel

oci

ty (

m/s

)

a) slope = rise/run =

b) slope = rise/run =

c) slope = rise/run =

d) slope = rise/run =

e) slope = rise/run =

7

Non-Uniform Acceleration this is when objects accelerate at different rates.

Ex. Find the acceleration during the various intervals.

8

Velocity vs. Time

0

5

10

15

20

25

30

35

40

0 1 2 3 4 5

Time (s)

Ve

loc

ity

(m

/s)

Assignment Velocity- time graph (11-10)

Velocity-Time Graph Is it still possible to find the displacement of the

object? The Area under the graph is the displacement• Length X Width

10

Describe the motion?How do you find the displacement??

Area and Displacement (12-8)

Displacement from Velocity- Time Graphs (12-10)