Question: How fast was the arrow moving before it joined the block?
Answer:
The arrow was moving at 15.9 m/s.
Explanation:
The law of conservation of energy says that the kinetic energy of the arrow must be converted into the potential energy of the block and arrow after it they join:
where 
is the mass of the arrow, 
is the mass of the block, 
of the change in height of the block after the collision, and 
is the velocity of the arrow before it hit the block.
Solving for the velocity , we get:
and we put in the numerical values
,
and simplify to get:
The arrow was moving at 15.9 m/s
Stars are huge celestial bodies made mostly of hydrogen and helium that produce light and heat from the churning nuclear forges inside their cores. Aside from our sun, the dots of light we see in the sky are all light-years from Earth. They are the building blocks of galaxies, of which there are billions in the universe. It’s impossible to know how many stars exist, but astronomers estimate that in our Milky Way galaxy alone, there are about 300 billion.
I’m pretty sure the answer is C. Any change of state or movement requires energy
#1
As we are increasing the frequency in the simulation the wavelength is decreasing
So if speed remains constant then wavelength and frequency depends inversely on each other
If we are in boat and and moving over very small wavelengths then these small wavelength will be encountered continuously by the boat in short interval of times
#2
As we are changing the amplitude in the simulation there is no change in the speed frequency and wavelength.
So amplitude is independent of all these parameter
Amplitude of wave will decide the energy of wave
So light of greater intensity is the light of larger amplitude
#3
In our daily life we deal with two waves
1 sound waves
2 light waves
The body will take 20 seconds to cover a distance of 1000 m i.e. 1 km
