Distance and Motion
St. Mary's HS

 

 

 

C. Acceleration - time rate of change in velocity (how quickly velocity is changing)

 

 

2 ways to have
 zero acceleration

 

 

a) remain at rest

 

 

b) constant velocity  

 

 

 

 

1. Equation

 

 

a = ∆V/∆t  = (Vf - Vi)/t

 

 

 

 

Ex 1

 

Starting Velocity: 5m/s West

 

Final Velocity: 25 m/s West

 

Time during speed change: 5 secs

 

 

 

a = (Vf - Vi)/(tf -ti)

 

 

 

a = 20 m/s W/5 sec

 

 

 

= 4 m/s/s West

 

 

 

 

or 4 m/s2 West

  

 

 

 

 

Ex 2)

 

Starting Velocity: 20m/s West

   

Final Velocity:5 m/s West

    

Time: 5 seconds

 

 

 

a = (Vf - Vi)/(tf -ti)

 

 

 

 a = -15m/s W/5 seconds =

  

      

= - 3 m/s/s West  

 

 

 

or -3 m/s2  W

 

 

 

or 3 m/s2 East

 

 

 


Object is said to be

 

 

'accelerating backwards'

 

(Because the force required to slow an object always opposes the objects motion)

 

 

 

 

 

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