Work of 44 joules is done in stretching a spring from its natural length to 18 cmcm beyond its natural length. what is the force (in newtons) that holds the spring stretched at the same distance (18 cmcm)?

Carbon is allowed to diffuse through a steel plate 15 mm thick. the concentrations of carbon at the two faces are 0.65 and 0.30 kg c/m^3 fe, which are maintained constant. if the preexponential and activation energy are 6.2 x 10-7 m2 /s and 80,000 j/mol, respectively, compute the temperature at which the diffusion flux is 1.43 x 10^-9 kg/m^2 -s.