Topic: Strength of Materials
Torque, T is applied at the free end of a stepped rod of circular cross section as shown in figure. If the shear modulus of the material is G, the angular twist, at free end will be
- A. 12TL / (G*pi*d^4)
- B. 24TL / (G*pi*d^4)
- C. 36TL / (G*pi*d^4)
- D. 48TL / (G*pi*d^4)
Answer: C. 36TL / (G*pi*d^4)
Explanation: When shafts are connected in series, total twist is theta_1 + theta_2. Theta = (TL/GJ)_1 + (TL/GJ)_2. Calculating polar moments of inertia for diamters d and 2d gives a total angular twist of 36TL / (G*pi*d^4).