4. Two boxes of mass 30.0 kg and 10.0 kg are at rest side by side, as shown below. You apply a force of 3.0 x 10" N on the first box for 5.0 s, and they both slide across the floor. The coefficient of kinetic friction between the boxes and the floor is 0.60. 30 kg 10 kg a) Calculate the acceleration of the boxes during the first 5.0 s. [A-2, C-1] b) Determine the magnitude of the contact force between the blocks while they are being pushed. [T-1, A-1, C-1] c) Calculate the total distance travelled by the boxes. [T-2, C-1]