Which term describes the twisting of an object due to an applied torque?

• A. The bending of a beam under load.
• B. The twisting of an object due to an applied torque.
• C. The stretching of a material under tension.
• D. The deformation under shear along a plane.

Answer: (D)

Twisting a component when a torque is applied is called torsion. When torque acts on a shaft or rod, its cross-sections rotate relative to one another about the axis, producing shear deformation that varies with radius. The material resists this twist with its shear modulus, and the amount of twist grows with length and with the applied torque, while geometry through the polar moment of inertia also plays a key role. This is different from bending, which curves under a bending moment; stretching, which lengthens under tension; or simple shear along a plane, which is a different mode of deformation that doesn’t inherently describe the axis-aligned twist caused by torque.