Getting someone to help you push your car out of a snowdrift. You both get on the same end of it and push in the same direction. Another beautiful example is a Tug-o-War, where you might have 50 people (!) all exerting force on the rope in the same direction.
If you all are doing the test on edgenuity then the answer is two football players pshing a tackling sled
Explanation:
