Prithvi II missile test-fired in Odisha

India test-fired its indigenously developed tactical nuclear-capable, Prithvi-II ,surface-to-surface short-range ballistic missile, capable of carrying 500kg -1000kg of warheads — as part of a user trial by the army from a test range at Chandipur.
With a strike range of 350km, and is thrusted by liquid propulsion twin engines. It uses advanced inertial guidance system with manoeuvring trajectory to hit its target. Inducted into India’s armed forces in 2003, Prithvi II — the first missile to be developed by DRDO under the prestigious IGMDP (Integrated Guided Missile Development Program) — is now a proven technology.
A missile is called ballistic because, just as one would throw a ball or spear, the rocket’s engine gives the missile an initial push, after which its flight is affected only by gravity. Ballistic missiles do not fly. They go up, and they come down. A ballistic missile can be launched from land, from a silo, from mobile platforms on trucks or trains, from submarine or ship, or from an airplane. After launch, a ballistic missiles arches up from one point, and lands at another point.
Inertial navigation, which relies on knowing your initial position, velocity, and attitude and thereafter measuring your attitude rates and accelerations. The operation of inertial navigation systems (INS) depends upon Newton’s laws of classical mechanics. It is the only form of navigation that does not rely on external references. Inertial navigation is a self-contained navigation technique in which measurements provided by accelerometers and gyroscopes are used to track the position and orientation of an object relative to a known starting point, orientation and velocity.
Inertia: the property of bodies to maintain constant translational and rotational velocity, unless disturbed by forces or torques, respectively (Newton’s first law of motion).

Gyroscopes are sensors for measuring rotation
Acceleration is a vector quantity that is defined as the rate at which an object changes its velocity. An object is accelerating if it is changing its velocity.
Velocity is a vector quantity that refers to the rate at which an object changes its position. Speed is a scalar quantity and does not keep track of direction; velocity is a vector quantity and is direction aware.
Scalars are quantities that are fully described by a magnitude (or numerical value) alone.
Vectors are quantities that are fully described by both a magnitude and a direction