The surface of a steel gear of 1022 steel (0.22 wt % C ) is to be gas-carburized at 927 oC. Calculate the time necessary to increase the carbon content to 0.3 wt% at 0.015 in. below the surface of the gear. Assume the carbon content of the surface to be 1.20wt%. D (C in iron ) at 927 oC = 1.28 x 10-11 m2/s. The answer should have one decimal of accuracy and be in minutes.

the aurora is formed when charged particles emitted from the sun during a solar flare penetrate the earth's magnetic shield and collide with atoms and molecules in our atmosphere. these collisions result in countless little bursts of light, called photons, which make up the aurora.

auroras are generated by charged solar particles hitting molecules in earth's atmosphere. this usually happens in high latitudes, because our planet’s magnetic field tends to funnel these particles toward the poles. that’s why it can be experienced in northern ohio.