Answer:
The angle of incidence is   
 
Explanation:
The diagram for this question is shown on the first uploaded image 
From the question we are told that 
    The distance between the mirror and the wall is  
     The height of the above the mirror is  
Generally the angle which the reflected ray make with the mirror is mathematically evaluated as 
              
substituting values 
              
             
From the diagram we can deduce that  the angle of incidence is 
              
So           
 
                
 
 
        
             
        
        
        
The impulse (the variation of momentum of the ball) is related to the force applied by

where 

 is the variation of momentum, F is the intensity of the force and 

 is the time of application of the force. 
Using F=1000 N and 

, we can find the variation of momentum:

This 

 can be rewritten as

where 

 and 

 are the final and initial momentum. But the ball is initially at rest, so the initial momentum is zero, and

from which we find the final velocity of the ball:
