question_answer

Three blocks A, B and C of masses 4 kg, 2 kg   and 1 kg respectively, are in contact on a 1   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

A)  2N                        

B)  6N                        

C)  8 N                       

D)  18 N                     

Correct Answer: B

Solution :

Given, \[{{m}_{A}}=4kg\] So total mass (M) = \[4+2+1=7kg\] Now,         \[F=Ma\Rightarrow 14=7a\Rightarrow a=2m/{{s}^{2}}\] FED of block A, \[F=F'=4a\Rightarrow F'=14-4\times 2\Rightarrow F'=6N\]