How heavy is a plastic bag? Not very heavy at all, but in order to use a plastic bag to help me karate chop a thin wooden stick, I don't need weight—I need air pressure. Below, the "Quick Clip" demonstrates the power of air pressure via the vacuum created between a plastic bag and the countertop.
WARNING: Use of video content is at own risk. Karate chopping wood with bare hands can damage bones or cause bruising. If the plastic bag or plastic wrap does not make an air-tight seal with the surface of the counter, the stick may fly out in a random direction with dangerous velocity.