Final answer:
IG2 indicates the type of navigation solution being used in physics, specifically the Inertial Guidance System that relies on accelerometers and gyroscopes.
Step-by-step explanation:
IG2 indicates the type of navigation solution being used in physics. In this context, IG2 refers to the Inertial Guidance System, which is a type of navigation system used in aircrafts and missiles. The Inertial Guidance System relies on accelerometers and gyroscopes to measure the acceleration and rotation of the vehicle, allowing it to calculate its position and maintain navigation even in the absence of external references like GPS.