Twobodies A and B of masses 5 kg and 10 kg in contact with each other rest on a table against a rigid wall . The coefficient of friction between the bodies and the table is 0.15.A force of 200 N is applied horizontally to A.What are (a) the reaction of the partition (b) the action-reaction forces between A and B ?What happens when the wall is removed? Does the answer to (b) change, when the bodies are in motion? Ignore the difference between mu_s and mu_k

Twobodies A and B of masses 5 kg and 10 kg in contact with each other

1.	Twobodies A and B of masses 5 kg and 10 kg in contact with each other rest on a table against a rigid wall . The coefficient of friction between the bodies and the table is 0.15.A force of 200 N is applied horizontally to A.What are (a) the reaction of the partition (b) the action-reaction forces between A and B ?What happens when the wall is removed? Does the answer to (b) change, when the bodies are in motion? Ignore the difference between mu_s and mu_k
Answer» Solution :We assume perfect CONTACT between bodies A and B and the rigid partition.In that case, the self-adjusting normal force on B by the partition (REACTION) equals 200 N. There is no IMPENDING motion and no friction.The action-reaction forces between A and B are ALSO 200 N. Whenthe partition is REMOVED, kinetic friction comes into play. Acceleration of `A+B = [ 200 - (150 xx 0.15 )]//15 = 11.8 ms^(-2)` Friction on A` = 0.15 xx 50 = 7.5 N` `200 - 7.5- F_(AB) = 5 xx 11.8` `F_(AB) = 1.3 xx 10^2 N` , opposite to motion `F_(BA) = 1.3 xx 10^2 N` , in the direction of motion