Predicate Logic Translations I'm currently learning predicate logic in university. I am doing a few predicate translations and just wondering if I'm on the right track.
A rectangle is a square unless its sides are different lengths.
Rx = x is a rectangle
Sx = x is a square
Dx = x has different length sides
∀x(Rx ⊃ (Sx v Dx))
For every action, there is an equal and opposite reaction.
Ax = x is an action
Ry = y is an equal reaction
Oz = z is an opposite reaction
∀x(Ax ⊃ ∃y∃z(Ry & Oz))
There is a barber who shaves all barbers who don’t shave themselves
Bx = x is a barber
By = y is a barber
Sxy = x who shaves y
Syy = y who shaves y
∃x∀y(Bx & (By ⊃(Sxy & ~Syy)))
 A: 
I am doing a few predicate translations and just wondering if I'm on the right track.

No.   Try first restating the English sentences with a sentencial logic structure.
For instance, "It is blue unless it is red" should be read as a conditional, "If it is not red, then it is blue."

A rectangle is a square unless its sides are of different lengths.

For anything: if it is a rectangle, then if its sides are not of different lengths, then it is a square.

For every action, there is an equal and opposite reaction.

For anything, there is something, if the former is an action then the later is an (re)action, the later is equal to the former, and the later is opposite to the former
(Note I: We are claiming the existence of something that is an equal-and-opposite reaction.)
(Note II: Is Opposite To and Is Equal To should be bivariate predicates)

There is a barber who shaves all barbers who don’t shave themselves

There is something, for anything: the former is a barber and if the later is a barber and the later does not shave themselves, then the former shaves the later.
