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

Question

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

Infinity Learn · Accepted Answer

Here, $$MA=4$$ kg,$$MB=2$$ kg,$$MC=1$$ kg,$$F=14$$ N Net mass, $$M=MA+MB+MC=4+2+1=7$$ kg  Let a be the acceleration of the system.  Using Newton's second law of motion, $$F=Ma14=7a$$  ∴  $$a=2$$ m $$s-2Let$$ F' be the force applied on block A by block B i.e. the contact force between A and B. Free body diagram for block A Again using Newton's second law of motion, $$F-F$$'$$=4a14-F$$'$$=4$$×$$214-8=F$$'∴  F'$$=6$$ N

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

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