Which force best represents Fg?

A weight lifter is pushing a barbell upward with a force of 90 N.
The weight of a barbell acting on a weight lifter is 80 N.
The amount of upward force of a table on a box is 25 N.
A box on a rough table has difficulty sliding past 25 N of force.

Aray of light traveling parallel to the principal axis of a concave mirror will be reflected through the mirror's

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.

Consider the following position function. find (a) the velocity and the speed of the object and (b) the acceleration of the object. bold r left parenthesis t right parenthesisr(t)equals=left angle 6 t superscript 4 baseline comma 2 t cubed right angle6t4,2t3 for tgreater than or equals≥0