Yeah, it's 4 cups, but that's a 15 tonne bus, and you can find 'a truck' lighter than that. Anyway, the ceramics blog reckons a single cup can take 10 to 15 tonnes. From an old textbook:
I reckon a coffee cup is roughly 1 inch radius, and 1/8th thickness; cross-section is 2*pi*r*t = about 0.8 square inches. That's about 7 tons, for that strength.
I don't think they're saying the one atom thick sheet would take it; it's scaling up the strength they have tested. For instance:
Now, researchers have discovered that graphene has remarkable mechanical properties too. Changgu Lee and Xiaoding Wei at Columbia University, New York, took flakes of graphene 10 to 20 micrometers in diameter and laid them across a silicon wafer patterned with holes just 1 to 1.5 micrometers in diameter, like a microscopic muffin tray.
The graphene above the tiny holes was unsupported, and Lee and Wei poked at these with the diamond tip of an atomic force microscope to see how readily the graphene deformed and ruptured.
They found that the graphene could be pushed downwards by 100 nanometres with a force of up to 2.9 micronewtons before rupturing. The researchers estimate that graphene has a breaking strength of 55 newtons per metre.
"As a way of visualising the force needed to break the membranes, imagine trying to puncture a sheet of graphene that is as thick as ordinary plastic food wrap - typically 100 micrometers thick," says James Hone, head of the laboratory at Columbia in which Lee studies. "It would require a force of over 20,000 newtons, equivalent to the weight of a 2000 kilogram car."
That strength puts graphene literally "off the chart" of the strongest materials measured, Hone says. "These measurements constitute a benchmark of strength that a macroscopic system will never achieve, but can hope to approach," he says.
http://www.newscientist.com/article/dn14354-atomthick-carbon-sheets-set-new-strength-record.htmlMaybe the truck/sheet over a coffee cup image is misleading; but, anyway, the cup can take it.