1. The problem statement, all variables and given/known data A 60 kg box which in turn pushes a 30 kg box move on wheels so friction is eliminated. The push is 30 N horizontially 2. Relevant equations What is the acceration on the system of boxes and what is Normal friction of the 60 kg box on the 30 kg box? 3. The attempt at a solutionThe normal friction is 9.8 x60 but I don't know if normal friction can only be hortizontal.