Ybus formed by inspection is   
 
  - 3.33i    0       3.33i   
    0      - 7.5i    2.5i    
    3.33i    2.5i  - 10.83i  
 
 Ybus formed after elimination of Bus 3   
 
  - 2.3060942i    0.7686981i  
    0.7686981i  - 6.9228994i  
 
 The power abgle equation is   

 Pe = 0.807 * sin(delta) 
 where delta is the machine rotor angle wrt to the infinite bus 
 The swing equation is   

 (5.00/180f) * d(delta)^2/dt^2 = 1.00 - 0.81sin(delta) 

 Intial Accelerating power is 0.616 per unit 

 Initial acceleration is 22.16*f 
 where f is the system frequency