I've heard that spring forces are generally non-impulsive as they don't really contribute to a change in momentum(of any body attached to it). How can we actually say that spring forces are non-impulsive? Is this because of the fact that springs are slow to adapt to any change made to it? Can someone provide me a more intuitive answer?(I'm just a 12th-grader!)
To me, that definition seems too specific and non-intuitive compared to the general concept of an "impulse" in physics.
An impulse in physics is typically defined as the integral of force over time. Determining the impulse will tell you how much the momentum of the object changed over that time period.
It's fairly trivial to show that over time, springs absolutely can change the momentum of an object they interact with. A trivial example is a object suspended by a spring which is first extended, and left alone to oscillate up and down. The velocity of the object connected to the spring is constantly changing, and it's mass remains the same. This means that the spring is changing the momentum of the object, and thus would be an impulsive force, as per the definitions I'm aware of.
Their version of "impulsive force" seems to be a specific definition, not the general physics definition. Wikipedia seems to shed some light on this:
The term "impulse" is also used to refer to a fast-acting force or impact. This type of impulse is often idealized so that the change in momentum produced by the force happens with no change in time. This sort of change is a step change, and is not physically possible. However, this is a useful model for computing the effects of ideal collisions (such as in game physics engines).
They seem to be using this specific definition of impulse. They are referencing specifically a fast acting force/impact. I personally find that overly restrictive, since the concept of impulse can be applied well beyond that range (as the wikipedia page for impulse shows). A related concept is the Dirac delta function; which is useful for measuring change in momentum of objects which interact over very short periods of time.
On another note, determining what is "fast-acting" is entirely relative and quite subjective. Depending on the mechanics of what is happening, an object interacting with a spring could be considered a "fast-acting" force, and thus an impulse. To really show how abstract it is, you could consider the forces of two billiard balls interacting to be a type of "spring force", as the interaction between them would approximately follow Hooke's law; just like springs.
A sufficiently stiff spring would behave much the same as billiard balls colliding, so I can't see how you could completely rule out springs having impulse forces, even when you define impulse forces as forces that act over a short timeframe. Given the wide range of spring properties, I don't think that statement is overly justified, though in context it might have made more sense.
I apologize for how wordy this got, I apparently had a lot to say.
An impulse by definition acts instantaneously (almost zero elapsed time). As a result a system under an impulse will have its momentum changed during this very short period of time. The forces acting during the impulse are in essence unknowable.
A spring is a force member that according to Newton's law changes momentum in a system gradually over time.
In summary, an impulse is a specified applied momentum, and a spring is a specified applied force.
I think you have read something that is, as Dale say, highly inaccurate. For the simplest case, take a block moving on a friction less floor and a spring attached to a vertical wall, some metres ahead. After hitting the spring, the mass will rebound in the opposite direction.
Or you can also consider a spring pendulum, (horizontal,not vertical (you can say gravity acts in vertical direction)). Very obviously, its momentum is changing continually.
And, as Jmac says, almost everything in this universe can be considered as a spring. You can compromise a tiny degree of rigidity to generalise it like that, but since there are no absolutely rigid bodies, I don't think that would matter.