To solve this problem it is necessary to apply the concept related to wavelength, specifically when the wavelength is observed from a source that is in motion to the observer.
By definition the wavelength is given defined by,
Where
= Observed wavelength
= Wavelength of the source
c = Speed of light in vacuum
u = Relative velocity of the source to the observer
According to our data we have that the wavelength emitted from the galaxy is 1875nm which is equal to the wavelength from the source, while the wavelength from the observer is 
Therefore replacing in the previous equation we have,
Solving for u,
Therefore the speed of the gas relative to earth is 0.02635 times the speed of light.
Answer: 10.8 g
Explanation: Density = mass/ volume
So, Mass = density * volume = 0.9 g/ml * 12 ml = 10.8g
The answer is 4. accelerating to move off the road as quickly as possible
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)
