For the following questions answer them individually
Which of the following stresses are associated with the tightening of a nut on a stud?
1. Tensile stresses due to stretching of stud.
2. Bending stresses of stud.
3. Transverse shear stresses acrossthreads. .
4. Torsional shear stresses in threads due tofrictional resistance.
Select the correct answer using the codes given below Codes:
A thin copper wire at $$300^\circ$$ is suddenly immersed in water at $$30^\circ C$$. It cools down to $$150^\circ C$$ in 70 seconds. It is then reheated to the initial temperature of $$300^\circ C$$ and suddenly exposedto air at $$30^\circ C$$ where it cools downto $$150^\circ C$$ in 200 seconds. This difference in cooling time is due to
The heat flow rate through parallel walls of thickness $$L_1, L_2$$ and $$L_3$$, having surface areas $$A_1, A_2$$ and $$A_3$$, thermal conductivities $$k_1, k_2$$ and $$k_3$$,
respectively, with the first and last walls maintained at temperatures $$t_1$$ and $$t_2$$ will be