Two blocks A and B of masses 3 kg and 2 kg respectively are placed in contact on a frictionless horizontal surface. A horizontal force of 25 N is applied on block A towards the right, and a horizontal force of 5 N is applied on block B towards the left. What is the magnitude of the normal contact force between the two blocks?

Step-by-step solution

Let the common acceleration of the system be a towards the right. The net external force on the system is F_ net = 25 - 5 = 20 N . Total mass of the system is m_ total = 3 + 2 = 5 kg . Acceleration a = F_ net m_ total = 20 5 = 4 m/s ^2 . Now, consider the free-body diagram of block B ( 2 kg ). The horizontal forces acting on it are the normal contact force N towards the right and the applied force of 5 N towards the left. Applying Newton's second law for block B : N - 5 = m_B a N - 5 = 2 4 N = 8 + 5 = 13 N . Answer