Acceleration and magnitude of contact force

[Joshw17_15]

Two blocks of masses m1 = 4.00 kg and m2 = 3.00 kg are placed in contact with each
other on a frictionless horizontal surface. A constant force F = 9.00 N is applied to the
block of mass m1. a) Determine the magnitude of the acceleration of the two-block
system. b) Determine the magnitude of the contact force between the two blocks.

 

[cepheid]

You haven't put anything in sections 2 or 3 of the template.

Hint for part a) what does Newton's 2nd Law say about the acceleration of the system?