Question

what do you understand by galilean invarience​

Answer 1

Galilean invariance or Galilean relativity states that the laws of motion are the same in all inertial frames.

Answer 2

hello dear here is ur answer

Galilean invariance or Galilean relativity states that the laws of motion are the same in all inertial (or non-accelerating) frames.

Galilean invariance or Galilean relativity states that the laws of motion are the same in all inertial (or non-accelerating) frames. Galileo Galilei first described this principle in 1632 using the example of a ship travelling at constant velocity, without rocking, on a smooth sea; any observer doing experiments below the deck would not be able to tell whether the ship was moving or stationary. The fact that the Earth orbits around the sun at approximately 30 km/s offers a somewhat more dramatic example, though it is technically not an inertial reference frame.

Specifically, the term Galilean invariance today usually refers to this principle as applied to Newtonian mechanics—that is, Newton’s laws hold in all inertial frames. In this context it is sometimes called Newtonian relativity. Among the axioms from Newton’s theory are:

There exists an absolute space in which Newton’s laws are true. An inertial frame is a reference frame in relative uniform motion to absolute space.

All inertial frames share a universal (or absolute) time.

Derivation

Galilean relativity can be shown as follows. Consider two inertial frames S and S’. A physical event in S will have position coordinates r = (x, y, z) and time t; similarly for S’. By the second axiom above, one can synchronize the clock in the two frames and assume t = t‘. Suppose S’ is in relative uniform motion to S with velocity v. Consider a point object whose position is given by r = r(t) in S. We see that

r′(t)=r(t)−vt.