Answer:
Seismic waves are mechanical waves because they travel through the medium of the Earth.
Explanation:
 
        
             
        
        
        
Answer:
3.57 m/s
Explanation:
The sum of the 2 momentums Is equal the finale momentums. so if momentums Is q, v Is velocity and m Is Mass, q3=m1*v1+m2**v2=16+9=25 m*kg/s
q3=m3*v3
v3=q3/m3=25/(4+3)=3.57m/s
 
        
             
        
        
        
Longitudinal, because the sound can only travel at one direction
        
                    
             
        
        
        
Yes, it can be unicellular and multicellular