according to the second law of dynamics F = m • a => a = F / m
 
        
                    
             
        
        
        
I am so sure it's 600,000 x 500 so you get 300,000,000
        
             
        
        
        
Seven days after a waxing gibbous moon, the moon will be waning gibbous, and at some point during that seven days, it will have been Full.
        
             
        
        
        
V: velocity of wave
f: frequency 
L: wavelenght
v = fL => L = v/f => L = (3x10^8)/(900x10^3) => L = 3.33 x 10^2m