physics
posted by Betty .
A force of magnitude 7.50 N pushes three boxes with masses m1=1.30kg m2=3.20kg, and m3=4.90kg. find the magnitude of the contact force between boxes 1 and 2. find the magnitude of the contact force between boxes 2 and 3.

the total mass is 1.3 + 3.2 + 4.9
the acceleration a = 7.5/that sum
therefore the force on the furthest box = m of that box * a
the force on the next box is that force + m that box * a
etc