Acceleration

AccelerationChange in

VELOCITY!!!

Need an equation

Magnitude

Direction

Review

x

t

xi

Slope = velocity

y=mx+b

x=vt+xi

What is slope?

Shows a Rate of Change

If slope is a rate of change, then what type of graph do I need to make an equation for acceleration?

or

Acceleration v=at+vi

-vi -vi

v-vi=at(v-vi)/t = (at)/t

v

t

vi

Slope =

y = m x + b

v

accelaration

=at +vi

Acceleration and UnitsUnits =

m/ss What do the units mean?

5 mi/hr :

For every hour of travel you move 5 miles.

12 (km/hr) / s :

For every second of travel your speed changes by 12 km/hr.Units always have a story to tell and that is why they are so important!

Acceleration and Units

15 m/s2

So if my speed increases by constant increments of 15 m/s each second, how does that affect the

distance I travel?

v=0m/s

v=15m/s

v=30m/s v=45m/s v=60m/s

The distance between points is NOT! constant. We travel greater distances because of our increasing speed.

Rank from least to greatest acceleration

Practice

Jimmy, after digging himself out of a sealed well, saw Jane standing down the road. His racecar can accelerate at a rate of 7 m/s2. Once Jimmy gets to a speed of 52 m/s Jane

will not be able to escape. How much reaction time does Jane have?

a = (vf-vi)/t7 = (52-0)/t

t = 52/7t = 7.43 s

Using tables to find acceleration

What is the position of the first object for the 8th second?

+ -

Magnitude and Direction

# + , -

Displacement

Velocity

Acceleration

In front of start placeBehind of start place

Moving Forward Moving Backward

• If v+, then speeding up•If v-, then slowing down

•If v+, then slowing down•If v-, then speeding up

v+a- =Slowing down

v-a- =Speeding up

Vectors