IB Physics Mass and Energy

A tutorial sheet on mass and energy. This is a topic of continual confusion. Notes for guidance are taken from the article by Keith Atkin in Physics Education 35, 5, Sep 2000, page 319.

1. Is matter the same as mass? No, matter is a qualitative term meaning substance, mass is a defined physical quantity which is a measure of inertia.
2. E = mc² states that mass (inertia) and energy are equivalent not interconvertible.
3. In the Cockroft-Walton reaction a proton interacts with a lithium nucleus forming two helium nuclei with a gain in kinetic energy. Is there a loss in mass? No, mass and energy are equivalent. Both energy and mass are conserved in the process, there is no destruction of mass or creation of energy. There is merely a redistribution of a fixed amount of energy (and its equivalent mass).