Which force best represents fg?
a. a weight lifter is pushing a barbell upward with a force of 90 n.
b. the weight of a barbell acting on a weight lifter is 80 n.
c. the amount of upward force of a table on a box is 25 n.
d. a box on a rough table has difficulty sliding past 25 n of force.

At very high pressures, gases become and will eventually a) more dense; become hotter b) more dense; change to a liquid or solid c) less dense; combust d) less dense; turn into a liquid

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.

Why do different substances have diffrent properties