<span>Birds which famous for performing a ritualized mating dance are: The Grebes
Grebes most commonly live near a fresh water source.
They conducted this ritual because When two Grebes with opposite sex dances near each other, they will release some sort of pheromones that make them attracted to one another. </span>
If you are pushing the coin across the table at a constant rate, the friction of the table and the horizontal force of your hand pushing are equal, and the coin itself moves at a constant rate. If you push a coin and let it go, there is no horizontal force keeping the coin going. Friction slows the coin to a stop. In both cases, the gravitational downward pull of Earth is equally but oppositely resisted by the upward push of table on the coin.
The rest energy of a particle is

where

is the rest mass of the particle and c is the speed of light.
The total energy of a relativistic particle is

where v is the speed of the particle.
We want the total energy of the particle to be twice its rest energy, so that

which means:


From which we find the ratio between the speed of the particle v and the speed of light c:

So, the particle should travel at 0.87c in order to have its total energy equal to twice its rest energy.
A spontaneous reaction is a term that is best describe to a type of reaction wherein it is started without even with the help of an outside force. In addition to that, this kind of reaction is commonly driven by the forces of enthalpy and entropy which are essential concepts to thermodynamics.