Angle of Twist

Q. The maximum shear stress in a solid shaft of circular cross-section having diameter d subjected to a torque T is $\tau$. If the torque is increased by four times and the diameter of the shaft is increased by two times, the maximum shear stress in the shaft will be

1. 2 $\tau$
2. $\tau$
3. $\tau$/2
4. $\tau$/4

Q. Maximum shear stress developed on the surface of a solid circular shaft under pure torsion is 240 MPa. If the shaft diameter is doubled then the maximum shear stress developed corresponding to the same torque will be

1. 120 MPa
2. 60 MPa
3. 30 MPa
4. 15 MPa

Q. Two shafts having same length and material are joined in series and subjected to a torque of 10 kN-m. If the ratio of their diameters is 2 : 1, then the ratio of their angles of twist is

1. 16 : 1
2. 2 : 1
3. 1 : 2
4. 1 : 16

Q. Which of the following terms represents the torque corresponding to a twist of one radian in a shaft over its unit length?

1. Torsional stress
2. Torsional rigidity
3. Flexural rigidity
4. Moment of resistance

Q. A solid circular shaft of diameter d and length L is fixed at one end and free at the other end. A torque T is applied at the free end. The shear modulus of the material is G. The angle of twist at the free end is

1. $\frac{16TL}{\pi d^{4}G}$
2. $\frac{32TL}{\pi d^{4}G}$
3. $\frac{64TL}{\pi d^{4}G}$
4. $\frac{128TL}{\pi d^{4}G}$

Q. A bar of circular cross-section of diameter D is subjected to a torque T at B as shown in the figure given below


What is the angle of twist at A?

1. Same as that at B
2. Zero
3. Twice as that at B
4. Half as that at B

Q. When a cantilever shaft of brittle material is subjected to clockwise twisting moment at the free end, the possible crack propagation will be

1. ${45}^o$ clockwise with respect to the axis of shaft
2. ${45}^o$ anticlockwise with respect to the axis of shaft
3. Perpendicular to the axis
4. Parallel to the axis

Q. Two solid circular shafts of radii $R_1$ and $R_2$ are subjected to same torque. The maximum shear stresses developed in the two shafts are ${\tau }_1$ and ${\tau }_2$. If
$\frac{R_1}{R_2}=2then\frac{{\tau }_2}{{\tau }_1}is$

1. 8

Q. A bar AB of diameter 40 mm and 4 m long is rigidly fixed at its ends. A torque of 600 Nm is applied at a seciton of the bar. 1 m for end A. The fixing couples $T_{A}and{T}_B$ at the supports A and B, respectively, are

1. 450 Nm and 150 N-m
2. 200 Nm and 400 N-m
3. 300 Nm and 150 N-m
4. 300 Nm and 100 N-m