Kinematics. Newtons Laws
posted by Natasha .
Two objects are in contact on a frictionless surface. A horizontal force is applied to one object as shown in the figure below. Use m1 = 1.2 g, m2 = 254 g and F = 0.7 N to find the force between the two objects.

Let f be the force between them, pushing on each other.
F  f = m1*a
f = m2*a
Ypu have two unknowns (a and f) and two equations.
Add the equations to get rid of f.
F = (m1 +m2)a
Now solve for f