let's assume that it's possible to maintain a object floating in the air, when we acelerate with the object there's basicly only one way to stop it, airbrakes.

let's assume that same object is traveling at a speed of 300 Km/h, is it possible to build a airbrake system able to fully stop the object in less than 1.5 seconds?

If it's possible to accelerate said object from 0 to 300 km/h in 1.5 seconds, then you should be able to do the opposite.

I don't know of anything with that sort of acceleration.

The braking system on an aircraft carrier is probably the closest thing. Or maybe a brick wall.

actually breaking an object isn't quite the same as acelerating it, when a object is traveling at an average high speed, in an ambient with a very low friction, it's very hard to break it easily, we need almost 4~5 times the energy to break an object travelling in the air that we need to acelerate it.

The braking system on an aircraft carrier is probably the closest thing. Or maybe a brick wall.

the brick wall is definitely not a solution.

but basicly, I wanted to know if it's theoricly and mechanicly possible to airbrake an object that weights aproximately 3000 Kg traveling at an average speed of 300 Km/h in 1.5 or less seconds.

Anything that gives it a reverse acceleration of 6g.
A big nasty-ass reverse thruster would do it. Perhaps a big enough parachute would as well, but I don't know how to calculate how big. You'd need an average force of 167000N (17 tonnes weight), but the maximum force for a parachute brake would be significantly higher.

If it were carrying a large ballast, maybe you could eject the ballast forward using springs, pneumatics, or hydraulics? Not practical, I think. You'd probably need a ballast several times larger than the object.

the brick wall is definitely not a solution.

but basicly, I wanted to know if it's theoricly and mechanicly possible to airbrake an object that weights aproximately 3000 Kg traveling at an average speed of 300 Km/h in 1.5 or less seconds.

if 3tonns of mass, moving 300km/h has to stop under 1,5sec or under then its basicly same as ramming the brick wall. Even 1tonn car moving 50km/h cant stop under 1.5 seconds.

It could if it ran into a haystack... that's not quite the same as a brick wall.

How about a directed explosion? ...similar to anti-missile protection on tanks, reactive armor.