Answer:
a
e(k) = \frac{2a}{c} * sin (\frac{k*a}{2} )
b
G_{v} = \frac{d e(k ) }{dk } = \frac{a^2}{c} * cos (\frac{k* a}{2} )
Explanation:
From the question we are told that
The velocity of transverse waves in a crystal of atomic separation is

Generally the dispersion relation is mathematically represented as

=> 
=> 
=> 
Generally the group velocity is mathematically represented as

Answer:
The neutron core is completely destroyed
Explanation:
A earth - supernova is an explosion resulting to the death of a star that occurs close enough to the earth but this does not completely destroy a star. Supernovae are the most violent explosions in the universe. But they do not explode like a bomb explodes, blowing away every bit of the original bomb. Rather, when a star explodes into a supernova, its core survives. The reason for this is that the explosion is caused by a gravitational rebound effect and not by a chemical reaction. Stars are so large that the gravitational forces holding them together are strong enough to keep the nuclear reactions from blowing them apart. It is the gravitational rebound that blows apart a star in a supernova.
Because of the greenhouse gases inside the greenhouse, and the gases trap the heat from the sun so the plant don't freeze, hope this helps
Answer: The gravitational
Explanation: The student is pushing the box so u have to have gravitational force so it could move