What would happen if earth's axis of rotation were not tilted but instead were perfectly perpendicular to the plane of its orbit around the sun?

Which is not one of the major climate zones? question 3 options: rain forest polar tropical temperate

Awave is produced in a rope. the wave has a speed of 33 m/s and a frequency of 22 hz.

Asheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200oc and is permitted to achieve a steady-state diffusion condition. the diffusion coefficient for nitrogen in steel at this temperature is 6 x 10- 11 m2 /s, and the diffusion flux is found to be 1.2 x 10-7 kg/m2 -s. also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 4 kg/m3 . how far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3 ? assume a linear concentration profile.