Answer:
From the formula of force:

since AB and k are constants:

x is a constant of proportionality
• when force is 4N, separation distance is 1

therefore, equation becomes

when r is doubled, r becomes 2. find F:

It's Z.
Without any force acting on it an object travels in a straight line.
In order to bend away from a straight line the object needs a force acting on it.
In order to move along a circle, the force on the object points toward the center of the circle. It's called the centripetal force.
Since the object's direction is changing it has acceleration.
The acceleration points toward the center of the circle.
Matter<span> doesn't </span><span>disappear </span>