Acceleration Review  

Acceleration - the time rate of change in velocity  

 

a = ∆V/∆t = (Vf - Vi)/t
 
Uniform Acceleration ???

 

 

 

- constant  change
in velocity per unit time

 

 

 

Which data shows uniform acceleration? Why?

time (sec) Velocity (m/s)
0 5
1 7
2 9
3 11
4 13
 
time
(sec)		 Velocity (m/s)
0 5
1 10
2 14
3 20
4 30

 

 

a = ?

 

 

a = 2 m/s2

 

 

Constant Acceleration?

 

 

 

 

 

 

Yes!

 

 

  

Every 2 seconds the object gains
exactly 15 m/s

 

Use a = ∆V/∆t
 to find the acceleration  

 

Answer: a = 7.5 m/s2

 

Slope of a V vs. t plot
tells us about the objects ...

 

 

... acceleration

 

Acceleration is ...

 

 

 

 

Zero

 

 

 

Velocity is ...

 

 

 

 

Constant

 

 

 

Describe Acceleration, Velocity

 

 

 

 

 

Velocity is decreasing,

Acceleration is constant, negative

 

 

 

Motion Graphs Animation (d vs t)

 

 

 

 

a = ∆V/∆t

 

 

 (15 m/s - 45 m/s )
     (8 sec - 2 sec)

 

= -5 m/s2

 

 

Describe acceleration and velocity

Velocity (m/s)

   

 




Acceleration is increasing

 

Velocity is increasing

 

 

 

Describe the velocity, acceleration

 

 

 

Velocity is increasing

 

Acceleration is constant & Positive

 

 

 

 

 

Describe velocity, acceleration

 

 

 

 

Velocity is decreasing

 

Acceleration is constant & negative

 

 

Analyzing Motion Plots - St. Mary's H.S.