Answer:
i hope this will help you :)
Explanation:
mass=19kg
density=800kg/m³
volume=?
as we know that
density=mass/volume
density×volume=mass 
volume=mass/density
putting the values 
volume=19kg/800kg/m³
so volume=0.02375≈0.02m³
 
        
             
        
        
        
GPE = 78,380 J
w = 39,240 N
First list what you know. You know the elephants mass and it’s height. You also know gravity on Earth. I will use g = 9.81.
m = 4,000 kg
h = 20 m
g = 9.81 m/s^2
You need to find the elephants weight. Weight = mass x gravity
w = mg
w = (4000 kg)(9.81 m/s^2)
w = 39,240 N (N = newtons)
Now, knowing the elephants weight, you can calculate its GPE. 
Gravitational Potential Energy = weight x height
GPE = wh
GPE = (39,240N)(20m)
GPE = 78,380 J (J = joules)
        
             
        
        
        
The sentence can be completed as follows:
"<span>A major difference between radio waves, visible light, and gamma rays is the 
energy of the photons, which results in the different photon frequencies and wavelengths."
In fact, gamma rays have greater energy than visible light and visible light has greater energy than radio waves. The energy E of a photon is related to its frequency, f, by
</span>

<span>where h is the Planck constant. We see from this formula that the higher the frequency, the greater the energy. Instead, the wavelength is inversely proportional to the frequency:
</span>

<span>where c is the speed of light. Since the frequency is directly proportional to the energy, this means that the wavelength is inversely proportional to the energy.</span>