Which type of force causes a body's position to change?

Unbalanced forces are not equal forces, and they cause an object's motion to change its speed and/or direction.

If two unbalanced forces are applied in opposite directions, the combined force equals the difference of the two forces.

As shown in the diagram, two boys are exerting force to push another boy. As a result of the greater force exerted by these two boys to push a lighter weight (50)N, he will move toward the higher force.

This is referred to as unbalanced force.

If  the forces acting on an object are out of balance, they do not cancel each other out. An unbalanced force acting on an object causes it to move. For example, the Earth attracts all objects. Friction caused by air resistance.