Answer:
A
Explanation:
half life is the time taken for a radioactive isotopes to dissociate 
 
        
             
        
        
        
Answer:
Hope it helps
Explanation:
The higher the bird flies, the bigger the shadow it casts, however, for the shadow to be visible enough the plane or bird would have to be close to the line directly from the sun.
 
        
                    
             
        
        
        
Answer:
a) 
b)  
  
c)  
     
Explanation:
a) The speed of a wave is given by the following equation:

Where:
λ is the wavelength
f is the frequency

b) The harmonic wave has the following equation:

A is the amplitude (2 m)
k is the wavenumber (2π/λ)  
ω is the angular frequency (2πf)
 
  
 
  
c) Here we need to find the heigth at x=3 m and t =10 s, so we need to find y(3,10).
 
 
 
               
 
               
I hope it helps you!
  
 
        
             
        
        
        
Answer:
B
Explanation:
It becomes lighter so it rises