A 2kg mass and a 4kg mass on a horizontal friction less surface are connected by a mass less string A. They are pulled horizontally across the surface by a second string B with a constant acceleration of 12m/s2.
What is the magnitude of the force of string A on the 4kg mass?
(A) 72 N
(B) 48 N
(C) 24 N
(D) 6 N
(E) 3 N