Why lighter bottles stay on better rather than heavy bottles? I was watching a Mythbusters video of them doing the table cloth trick and Adam says that the lighter bottle worked better. Don't heavy bottles (more mass) have more inertia and therefore should work better? Can someone explain? I couldn't find an explanation.
 A: You are correct in saying that heavy bodies do have a larger inertia, however, heavier bodies also exert a larger normal force on the table and thus the friction force acting on them is also comparatively larger (since frictional force is proportional to the normal force, $f=\mu N$).
This means that while pulling, the larger frictional force will generate a larger torque and thus the heavier bottle will not let the table cloth slip beneath it, rather the bottle itself will start rotating. Thus it is due to this aspect that heavier bottles don't work well for this trick. But if the bottle is light enough, then the friction force will also correspondingly be lower (due to a smaller normal force) and thus the bottle will easily slip when we pull the table cloth.
However, do note that there are many other factors also at play here. You might observe completely different results if you repeat this trick with different cloth or a differently shaped bottle. So this observation isn't universal.
