what will happen if the force is completely removed when an object acquires a certain speed
Answers
If the forces are completely removed when an object acquires a certain speed(say v), then the object will move with that velocity(v) at a constant rate.
Explanation:
Imagine a block(object) being pushed by a constant force 'F' (F here includes all the conservative forces, the questioner may have assumed) for a time period 't', and after that time period, it acquires a speed 'v'.
Now, when the force 'F' is completely removed from the object and assuming that there are no other non-conservative forces ( like Friction, air friction, etc), the block will move with the constant velocity 'v' that it acquired when the external force 'F' was acting on it.
It can also be explained by Newton's 2nd law of motion, which states:-
F = ma
Here, when force (F) becomes 0, acceleration (a) also becomes 0, because the mass (m) can't be 0 in any case.
Taking into account this equation:-
a = change in velocity / time period
And proceeding further with it, if acceleration is 0, then velocity (v) becomes constant.
Hence, it is proved that the block will move with a constant velocity when all the external forces are removed from that block.