Answer:
Unbalanced forces cause acceleration.
Step-by-step explanation:
They cause acceleration because one force is less or more in Newtons than the other force.
For example, let's say we have a cardboard box on the floor with no friction.
If one force is pushing the box to the right with 50 Newtons, and the second force is pushing the box to the left with 0 Newtons, the box would accelerate to the RIGHT because the forces are UNBALANCED.