[img]http://4.bp.blogspot.com/-yN5JohxQD9M/VGj0sD9tr2I/AAAAAAAACHk/gt2AqBDPxu4/s1600/33.jpg[/img]

[img]http://2.bp.blogspot.com/-Mry0nxUU74M/VGBy5Uta3pI/AAAAAAAACFg/B68sugnYIr4/s1600/MMR.jpg[/img]

[size=30pt]very nice problem is
how heavy is Air ?

light is able push objects
http://en.wikipedia.org/wiki/Solar_sail


more about problem
http://maroszphysics.blogspot.com/[/size]