Physics
Physics
Problem
Define the Q-value of a nuclear reaction and state what the sign (positive or negative) of the Q-value indicates about the energy aspect of the reaction.Intuitive explanation
The Q-value measures the net energy released or absorbed when nuclei rearrange during a reaction—it's the difference between the rest mass energy of reactants and products. A positive Q means the products are lighter than the reactants, so mass converts to kinetic energy and the reaction is exothermic (spontaneous). A negative Q means you must supply energy to make the reaction happen, since the products are heavier and the reaction is endothermic. Understanding Q-value is essential for predicting whether a nuclear process releases usable energy or requires an energy input.
Intuitive explanation
The Q-value measures the net energy released or absorbed when nuclei rearrange during a reaction—it's the difference between the rest mass energy of reactants and products. A positive Q means the products are lighter than the reactants, so mass converts to kinetic energy and the reaction is exothermic (spontaneous). A negative Q means you must supply energy to make the reaction happen, since the products are heavier and the reaction is endothermic. Understanding Q-value is essential for predicting whether a nuclear process releases usable energy or requires an energy input.