Three blocks of mass m1=1.0 kg, m2=2.0 kg, and unknown mass m3 are on a frictionless forizontal surface as shown on the figure below. The blocks are connected by ideal massless strings. A force FL=15 N is applied to the left block and is directed to the left. A force FR=33 N is applied to the right block, and is directed to the right. The tension T12 in the string between m1 and m2 is not known and the tension T23 in the string between m2 and m3 is 24 N.
(a) What is the acceleration of the system?
(b) What is the tension T12 in the string between m1 and m2?
(d) What is the unknown mass m3?