Three blocks A, B and C of masses 4 kg, 2 kg and 1 kg respectively are in contact on a frictionless surface as shown. If a force of 14 N is applied on the 4 kg block, then the contact force between A and B is

Given,  m A = 4kg,  mB = 2kg  and  m C = 1kgSo, total mass, M = 4 + 2 + 1 = 7 kgNow,  F = Ma  ⇒ 14 = 7a  ⇒  a = 2ms-2FBD of block A ,F - F' = 4a ⇒ F' = 14 - 4 × 2  ⇒ F' = 6 NHence, the contact force between A and B is 6N.