They share electrons because it is a covalent bond
Answer:
v₁ = 4 [m/s].
Explanation:
This problem can be solved by using the principle of conservation of linear momentum. Where momentum is preserved before and after the missile is fired.

where:
P = linear momentum [kg*m/s]
m = mass [kg]
v = velocity [m/s]

where:
m₁ = mass of the tank = 500 [kg]
v₁ = velocity of the tank after firing the missile [m/s]
m₂ = mass of the missile = 20 [kg]
v₂ = velocity of the missile after firing = 100 [m/s]
![(500*v_{1})=(20*100)\\v_{1}=2000/500\\v_{1}=4[m/s]](https://tex.z-dn.net/?f=%28500%2Av_%7B1%7D%29%3D%2820%2A100%29%5C%5Cv_%7B1%7D%3D2000%2F500%5C%5Cv_%7B1%7D%3D4%5Bm%2Fs%5D)

Explanation:
Natural length of a spring is
. The spring is streched by
. The resultant energy of the spring is
.
The potential energy of an ideal spring with spring constant
and elongation
is given by
.
So, in the current problem, the natural length of the spring is not required to find the spring constant
.

∴ The spring constant of the spring = 
Answer
given,
copper rod length = 50 cm
density of the copper = 8.92 g/cm³
iron rod length = 50 cm
density of iron = 7.86 g/cm³
mass of iron = density × volume
m_i = 7.86 × A × l/2
m_c = 8.96 × A × l/2
taking the intersection of copper and iron rod be starting point cooper side is taken as positive side and iron side length is taken to be -ve side.
center of mass
= 
= 
= 
= 
= 0.015793 m
= 1.579 m (+ve)
center of mass shift to cooper because cooper is heavy.