Three masses m1, m2 and m3 are being pulled by force F (Figure). Strings connecting m1 to m2 and m2 to m3 are massless. The coefficient of kinetic friction between masses and table is 0.1. If m1 = 20 kg, m2 = 30 kg and m3 = 50 kg and F-1500N then(a) What is the acceleration of books?(b) What are the tensions in strings tied between m1 and m2 and m2 and m3?

Let T₁ = Tension in the string tying m₁ to m₂.

and T₂ = Tension in the string tying m₂ to m₃.

Free body diagram for the masses and corresponding equations are

T₁–µ_km₁g = M₁a

T₂–T₁–µ_km₂g = m₂a

F–T₂–µ_km₃g = m₃a

Solving these equations we get

(a)    m₃a = F–µ_kg(m₁+m₂+m₃)–m₁a–m₂a

= 14.02 m/s²

(b)    T₁ = m₁ a + m₁ µ_k g

T₁ = 20 (14 + 0.98) = 299.60 N

T₂ = 299.60 + 30 × 14.98 = 749 N