A point.
(Also time, language, concepts, etc.)
B point
This would be a line, which has no width, no thickness and no endpoints, but has infinite length.
A plane
a point
A line fits this description.
Most stone table tops and benchtops are at least 20mm thick, but they will require support for the stone along the full length and width at this thickness.
A point has no length, width, or thickness. A line has infinite length but no width or thickness. A plane has infinite length and width but no thickness.
Time has no length, width or thickness.
A line has infinite length, no width, no thickness, and no endpoints.
This would be a line, which has no width, no thickness and no endpoints, but has infinite length.
A point.
If the bar is a three dimensional object it will have some thickness. Then, assuming it is oblong in shape and knowing its length, width and thickness: Surface_area = 2 x (length x width + width x thickness + thickness x length)
Length
A plane figure
capicity=length*width*thickness
Length times width times thickness
It is Length.
Density = Mass / Volume the Volume is what you just said ... length x width x thickness