If a house of cards collapses, its weight does not change due to the collapse. It still weighs 45 grams, assuming no cards were added or removed, and no part of the cards was lost or destroyed during the collapse. The shape and structure may have changed with the collapse, but the mass remains the same. Every physical object, such as a house of cards, has a property called mass, which is constant in a given environment regardless of its shape or structure unless physical material is added or removed.
