Nitrogen, oxygen, and argon
        
             
        
        
        
Answer:78 N
Explanation:Impulse=Force*time
 =39*2 =78 Ns
 
        
             
        
        
        
The problem of the "sound barrier" has to do with moving through 
air, and the things the air does when you try to push it out of the 
way faster than the speed of sound.  Moving through air faster 
than sound was an engineering and technological problem, not 
a scientific one.
Concerning light, that's about 874 thousand times faster.  
See the problem ?
        
             
        
        
        
Answer
given,                            
mass of the piano = 170 kg              
angle of the inclination = 20°                 
moves with constant velocity hence acceleration = 0 m/s²    
neglecting friction                                   
so, force required to pull the piano                    
F = m g sin θ                                                      
F = 170 × 9.81 × sin 20°                                         
F = 570.39 N                                                    
so, force required by the man to push the piano is F = 570.39 N