PLEASE HELP​

Can somebody explain to me how newton's 3rd law relates to momentum? ~ap physics 1

If the temperature were raised very high, classically what would we expect the heat capacity per object to be for this one-dimensional system? give a numerical value. chigh t = __ j/k/object (one reason for the discrepancy is that the high-temperature limit assumes that the number of oscillators is large (n > > 1), which is not the case in this tiny system.)

Which atomic model was proposed as a result of j. j. thomson’s work?