Aforce that causes an object to change its motion is called a(n) a. unbalanced force b. resistant force c. compound force d. unnatural force

I believe it is A. Unbalanced.

Explanation:

Hope i helped you!

Unbalanced force causes an object to change its motion.

Option A

Explanation:

A force can be explained as push or a pull that has the tendency to change the velocity of a mass.

The force that makes any change in the movement of an object or body is known to be an unbalanced force. These forces are not equal and opposite. When an object is placed in a rest position and when unbalanced force acts on it, this will not make the object to move.

Example: Force applied against the ball.

The forces whose size is equal and opposite in their direction are known as balanced force. These forces will not make any change in motion of a body. When an object is placed in a rest position and when balance force acts on it, this will not make the object to move.

Example: Pushing against a wall.  

double the distance = divide strength by 4