Mass and Inertia
What is mass?
Mass is the amount of matter in something regardless of forces that act on it. Or how heavy it is...which is more of a laymen term. We measure how much matter an object has with grams and kilograms.
The higher the mass, the more matter it has, and hence the heavier it is.
Mass does not change even if gravity changes i.e. your mass will remain the same even if you are on Mars or the Moon. The only way for mass to change is when you remove some matter, for example cut a limb off an animal or rip a section out of the book. In both cases the object loses a bit of matter and hence the mass changes.
What about Inertia?
Inertia is basically how much resistance an object has to force. What's that? Well, that basically means how hard it is for something to move. The larger the inertia, the harder it is to move that object. Inertia is directly related to mass - in fact mass is solely dependent upon the inertia. That means the higher the inertia, the more mass there is. The more mass there is, the more motion and change that object can resist. For example, it is easier to push a plastic lego sculpture than a marble sculpture, because the marble sculpture has more mass and therefore is harder to move. Fun Experiments
Place a couple of books or bricks on someone's head, and hit the top of the pile with a hammer. Theoretically, he will not feel anything for the stack will have a huge mass, and thus a huge momentum, resisting change in motion that will result in an impact on the boy's head. Common Misconceptions 1) Mass is NOT weight in Physics! Weight is another thing which will be discussed later! 2) Intertia is not affected by speed - only the mass of an object will change its momentum.
