When two forces act in the same direction, the net force is their addition.

Which of the following statements is/are true?

1. Forces in the same direction add up.

2. Two forces in opposite directions resulting in net force, equal to their difference, in the direction of the larger force.

3. Change in either direction or magnitude of a force changes its effect.

4. When more than one force is acting on an object, the effect on the object is due to the net force acting on it.