A.Bubble wrap is made of 2 sheets of heated plastic, 1 laid on top of the other. The top layer is then sucked through a circular mesh forming the bubbles.
A.Bubble wrap was invented by engineers Alfred Fielding & Marc Chavannes in 1957. It was an accident; they were trying to make textured plastic wallpaper.
Q.Is it bad to crack your knuckles and what is making the noise
A.The click when you crack your knuckles and other joints is the sound of bubbles bursting in synovial fluid around the joint. It doesn't cause arthritis.
Q.How are the bubbles in beer formed
A.The bubbles in beer are formed from carbon dioxide gas & so they are lighter than liquid. This is why the bubbles float up from the bottom of the glass.