91Ó°ÊÓ

The energy possessed by an item as a result of its location in relation to other objects, internal tensions, electric charge, or other causes is known as potential energy.

In order to find physical significance of quantity A,B and C look state 4 in the diagram should be considered.

Note that A,B and C are magnitudes, therefore it can be concluded that A is the magnitude of the potential energy U, when the separation between the atoms is ${\mathrm{r}}_1$since U is negative at this separation.

The horizontal green lines, represent states in which the total energy of the system remains constant that is:

K+U=E

E = constant

Note that in this model no non-conservative forces are considered and so, energy is conserved. This means that C is the magnitude of the total energy of the system which happens to be negative when the separation is equal to ${\mathrm{r}}_1$.

Finally, it is concluded that the kinetic energy is equal to B , because it is the energy that has to be added to U (that would be -A) in order to obtain the total energy (which would be -C).

Therefore, we can conclude that $A=\left|U\right|,B=K\mathrm{and}C=\left|K+U\right|$.

In order to know which states are bound and which are unbound, consider only two states 4 and 5 . Note that a bound state is that in which a particle tends to be located in a delimited region of space.

Also, note that in state four the particle has no kinetic energy at the two limiting points in this state, this means that particle 5 will tend to stay in the region delimited by U , the same happens for state 1,2 and 3, which are below 4 and so, have the same condition.

This does not happen in state 5, which only has zero kinetic energy at the lowest separation between the atoms, as result the atoms can separate indefinitely.

Therefore, it can conclude that 1,2,3 and 5 are bound states and is an unbound state.