Inertia experiment 2

The two margarine tubs are supposed to look identical but one is full of sand and is much heavier. Pull the paper gently - one with each hand - and you can feel the difference but both move. Then give the papers a sudden tug.

The heavy one stays where it is but the light one is more likely to fall over. The heavy object has inertia. If an external force acts it is more likely to carry on doing what it was doing beforehand - in this case, staying still. Newton's First Law again.