3. Two boxes of masses 2 kg and 4 kg is connected using a light string and placed on a smooth surface. 18 N force is applied on 2 kg object as shown in the diagram below. The friction force on 4 kg box is 4 N and the friction force on 2 kg box is 2N, Determine the tension of the string and acceleration of the blocks. Fles 2kg - 18 N 4. An object of mass m, resting on a horizontal frictionless surface of coefficients of static friction 0.3 and coefficient of kinetic friction 0.25 is acted upon by applied force of F. Find the friction force acting on the object when (Give only one answer for the friction force. Write your final answer in the box.) (a) F = 4 N Horizontal and m = 2.0 kg, 2/4 3 4N (b) F = 24 N horizontal and m = 6 kg, 16 ka ) 24N