PHYSICS HELP - force, acceleration, etc.?

Question

UNIT 3, LESSON 11, PAGE 32

24. Peter and Jon and playing a game of tug-of-war on a frictionless, icy surface. Peter weighs 539 Newtons and John weighs 392 Newtons. During the course of the game, John accelerates toward Peter at a rate of 3.0 metres/second^2.

A) What is the magnitude of the force that Peter exerts on John?

B) What is the magnitude of the force that John exerts on Peter?

C) What is the magnitude of Peter’s acceleration toward John?

D) Sarah decides to join the game as well. Now Peter pulls on Sarah with a force of 45.0 Newtons [E], and John pulls on her with a force of 25.0 Newtons [N]. What is Sarah’s resultant acceleration, if she weighs 294 Newtons?

Answer 1

(C) m1a1 = m2a2
(w1/g)a1 = (w2/g)a2
w1a1 = w2a2
a1 = w2a2/w1
a1 = (392)(3.0)/539
a1 = 2.1818m/s^2
(A) f = ma
f = (w/g)a
f = (539/9.8)(2.1818
f = 120N
(B) f = (w/g)a
f = (392/9.8)(3.0)
f = 120N
(D) If they're both males are pulling in the same direction:
f = ma
a = f/m
a = f/(w/g)
a = fg/w
a = (45 + 25)(9.8)/294
a = 2.33m/s^2