Question

Consider the following statements
(A) For the two shafts connected in parallel, the angle of twist of each shaft is same.
(B) For the two shafts connected in series, the shear stress in each shaft is same.
(C) The shear stress in a circular shaft under torsion varies linearly.
(D) The shear stress at the centre of a circular shaft under torsion is zero.
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only.
• B. (A), (C) and (D) only
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

In torsion shear stress is directly proportional to the distance from the center of the shaft. The center experiences no shear stress.

Answer 1

The Correct Option is B

Statement A is true; parallel shafts experience identical angles of twist.
Statement B is false; shear stress in series-connected shafts varies with their lengths and resistances.
Statement C is true; for a circular shaft in torsion, shear stress rises linearly from the center to the surface with increasing radius.
Statement D is true; a shaft under torsion has zero shear stress at its center, increasing with radius towards the outer surface.