Let’s say you now know that it takes 450 joules of work to move the rock 3 meters with you and your friend each exerting 75 newtons of force. This time, you suggest to your friend that it might be easier if you got some more help, and you get another friend to help. Assuming that it still takes 450 joules of total work to move the rock 3 meters, and there are now three of you, how much force do you each need to exert in order to move the rock? Since the work and the distance have stayed the same, the total force must also remain the same. The total force is still 150 newtons. The total force of 150 newtons divided among three of you means that each of you will need to exert 50 newtons of force if there are three of you pushing the rock.
What if you push against a huge rock and you can’t even budge it? No work is done if the rock doesn’t move, even though you use lots of energy and exert a lot of force in trying to move the rock. Work occurs only when a force succeeds in moving the object that the force acts on!
