The speed of a car is increased uniformly from 20. meters per second to 30. meters per second in
4.0 seconds. The magnitude of the car's average
acceleration in this 4.0-second interval is

if the forces acting on an object are unbalanced, the object will accelerate in the direction of the net force on the object.

explanation:

this is best explained by having an understanding of newton's second law, which states that f=ma. you see, when the forces are unbalanced, net force (sum of all forces) is not zero. therefore making it necessary for the object to have an acceleration in the direction of the net force.