An object accelerates when all the forces acting on it don't add up to zero.
it does not accelerate
If a force is being applied to a moving object, it will change its velocity (it will accelerate) appropriately.
by adding more force
Any force.
An unbalanced force will always make an object accelerate. If the object is at rest, it will start moving.
An unbalanced force will always make an object accelerate. If the object is at rest, it will start moving.
The object is accelerated in the direction of the net (or resultant) force.
Not all moving objects accelerate. In general, an object will accelerate if there is a net force acting on it. For a ball in the air, this might be gravitation + air resistance; for a moving car (once you turn the engine off) it might be the force of friction; etc.
If forces on an object are unbalanced, the object will accelerate or decelerate. If forces on an object are balanced, the object will stay still or keep moving with the same velocity.
If forces on an object are unbalanced, the object will accelerate or decelerate. If forces on an object are balanced, the object will stay still or keep moving with the same velocity.
It will not accelerate. That means that its velocity won't change.
An object will accelerate in the direction of the net force acting on that object.