Question

Three identical blocks of masses m = 2kg are drawn by a force F =10.2N with an acceleration of 0.6ms^–2 on a frictionless surface, then what is the tension (in N) in the string between the blocks B and C?

(a) 9.2 

(b) 7.8 

(c) 4 

(d) 9.8

Answer 1

(b) : Therefore,  Force = mass × acceleration
Therefore,  F – T_AB = ma
and T_AB – T_BC = ma
Therefore,  T_BC = F – 2ma
or T_BC = 10.2 – (2 × 2 × 0.6)
or T_BC = 7.8N.