A plastic bar of 53 mm is to be twisted by torques T until the angle of rotation between the ends of the bars is 9 degree. If the allowable shear strain in the plastic is 0.018 radian, what is the minimum permissible length of the bar in mm?

The tube has a length of 2 m and is made of the material with the properties provided in the following figure. (a) Determine the torque needed to just cause the maximum strain to reach 0.015. (b) What is the permanent angle of twist of the tube when this torque is removed?

The error in a measurement due to strain when using a tape measure depends on the material that it is made of. For a tape with a cross section of 10 mm by 0.7 mm, calculate how much error is introduced in inches into the measurement at a 300 ft length if the tape is pulled with 80 N and if the tape is made of: a) mild steel (E = 30 x 10^6 psi), b) polycrystalline aluminum (E = 10 x 10^6 psi) c) fiberglass composite (E = 3.5 x 10^6 psi in the long direction)

A helical spring used in an automobile suspension is having a wire diameter of 7mm and an outside diameter of 72mm. The spring has 16 active coils. If the permissible shear stress of the spring material is 345 N/mm2 and the Modulus of rigidity is 83 kN/mm2.   a) Calculate the axial load in N and the deflection of the spring in mm, considering the effect of curvature. b) Calculate the value of axial load in N neglecting the effect of curvature.