What is rest mass?
How to explain it especially to the high school students? Asked by: Alper Akyurek Answer One of the consequences of Einstein’s special theory of relativity (1905) is that the mass of an object increases with its velocity relative to the observer. When an object is at rest (relative to the observer), it has the usual (inertial = tendency to resist an applied force) mass that we are all familiar with. This is called the ‘rest mass’ of the object. As the speed of the object is increased, the inertial mass of the object also increases. For speeds significantly less than the speed of light, the increase in mass is nearly imperceptible, but as the speed of light is approached, the mass starts to increase very rapidly toward infinity. Theoretically, the mass would become infinite if the object could be accelerated all the way to the speed of light. However, because the acceleration of an object in response to a given force is inversely proportional to its inertial mass, as the speed of light
