An empty barrel weighs 9 kilograms What can you put in the barrel to make it weigh 8 kilograms?

Wait a couple of hundred years and put anti-gravity in it.

Put air in it and take it on a ride on the vomit comet aircraft to have the barrel experence weightlessness.

Maybe you could just take the top off and let it fill with the sorrounding air and it will weigh

less while the top is off.

BEST ANSWER: A HOLE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!11