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Question

Three masses are connected together by strings. Starting from left and going right, mass 1 is 12kg, mass 2 is 24kg, and mass 3 is 31kg. The force applied to the string attached to mass 3 and is pulling right is 65N. (a) Find the acceleration of the system (b) find the tension in the string between mass 1 and mass 2 (c) between mass 3 and mass 2. Assume no friction

Answer 1

T1=m1*a, no matter are there m2 & m3 or not.
T2=(m1+m2)*a, no matter whether m1 & m2 are connected with a string or are in one lump, the presence of m3 being unimportant too.

Answer 2

a) F=ma,
or a = F/m = 65/(12+24+31)=0.97014m/s^2