Two forces F1 and F2 are acting on a mass M=6.0 kg. The force F1 = 7.0i + 5.0j + 6.0k, in N. The acceleration of the mass is given by a = 1.0i + 3.0j + 3.0k, in m/s2. Calculate the magnitude of F2. I understand that when adding these forces you just add like terms, the i's j's and k's togehter. but what do you do with accel.? do i just subtract F1 like terms with Acell. like terms? never done a problem like this before.