If the object accelerates, that means the forces are NOT balanced.

This is a weirdly worded question but friction.

friction is the reaction to motion

Whether they are, or are not, exerted depends on the physical situation. For example, magnets won't lose their magnetic force if you make them touch. And if objects stick together, they are certainly exerting a force on one another.

Pushing a ball in a vaccum is an example of inertia because there is no resistence to stop the ball so the ball would keep going.

The tendency of an object to do nothing unless an external force gives it a prod. In humans, a preference or disposition to remain inactive. Put simply, intertia means things like to keep doing what they're already doing unless prompted to do something else.
Inertia is one of Newton's laws of motion. An object in motion (or in rest) will stay in motion (or in rest) unless acted upon by an unbalanced force. You can think of it as if you were sitting in the seat of a car and the breaks get slammed on.. the idea of inertia is that, because you were in motion while in the car, you would continue to go in motion but the seatbelt or the dashboard stop you.

netwons 3rd law

If net force acting on a mass decreases, the acceleration of the object decreases.

But if the mass of an object were to decrease while a constant net force acted on it,

its acceleration would INcrease.

If the net force on the object AND the object's mass both decrease, the object's

acceleration could either increase OR decrease. We'd need the actual numbers in

order to calculate how it would turn out.

a book kept on a table. no change in its state of rest unless some external force applied.

however in case of moving bodies no such easy example's there as friction always supplies the retarding force ultimately bringing body to rest.

No. All materials have the slightest bit of friction. Even if an object may look smooth to the human eye, it has a microscopic jagged side. Even something as smooth as ice has a little friction

Its what moves everything.

We've spent the last 500 years trying to get used to the idea that no force is required

in order for an object to move. Force is required only to change the speed or direction

of an object's motion, but the object keeps moving just fine at a constant speed and in

a straight line, forever, with no forces on it.

4 meters per second squared

yes it does

yes

In theory, no but in real life, there is always some object whose gravitational force acts on the object. Even if you were in the vacuum of outer space, quantum fluctuations would result in pair of matter and anti-matter appearing and disappearing. But during their fleeting existence they would result in tiny, tiny, tiny gravitational forces acting on you.

Second Law of Motion: Acceleration is produced when a force acts on a mass. the greater the mass ( of the object being accelerated) the greater the amount of force needed ( to accelerate the object).

"The rate of change of momentum is directly proportional to the impressed force and acts in the direction in which the force acts"

Acceleration "a" varies directly proportional to "F" the impressed force.

F = m x a

a = F/m

A force is required to change momentum.An "impulse" refers to the amount of momentum transferred; impulse can be defined as force x time (more precisely: the corresponding integral).

the first law is more of about establishing a reference frame for the other two laws of motion. The first law is about inertia. It simply states that something will not change speed if there is no force acting on it.

a ball on a trolley is a good example, because when you pull the trolley, the ball moves backwards in the trolly, but doesnt move relative to the ground, the reason being that no forces are acting on the ball itself. Air hockey is another example, we will assume for this examply that its surface goes on forever. The air reduces the amount of friction, friction is a force. With no air, the puck can be pushed , but will come to a stop quite quickly, but with a reduction in friction, i.e. the air turned, it would take a lot longer for the puck to stop. Intuitively (this isn't quite rigourous), we can say that zero friction causes the puck to continue moving indefinitely.

But, for a complete understanding , you should take newtons laws together, rather than one at a time.

A reaction force is bascally a force that acts in the opposite direction to an action force. It can better be described as when one fires a bullet from a gun, they feel being pushed backward. The action force in this case is the gun pushing out the bullet and the reaction is the bullet pushing back on the gun and its holder.

A force, that may come from a collision with ...

Another object.

Newton's first law of motion was the law of inertia. When an object is in motion, it stays in motion. When an object is in rest, it stays in rest.

Add the different forces together to find the net force. For example, if you have a force of -5N acting on an object and another force of 8N acting on that object, the net force is 3 N.