Some early teens have trouble understanding Newton’s laws of motion. To better understand these laws, we must tell the story of an average boy going about his day.
It was a typical sunny Saturday. 13-year-old Billy is in his basement doing laundry. When he bends over to pick up a dropped sock, he comes across something strange. He spies a door behind the hot water tank. He has looked at the wall behind the tank before and this door had never been there. At first, he is confused, but his curiosity gets the better of him, so he decides to open the door. When he opens the door, he is shocked! Behind the door is an exact copy of his house! He decides he should try to figure out if this is some sort of alternate universe with different properties. He can’t seem to find any of his family members though.
He decides to work on an experiment on his own. Looking outside, he realizes that it is night, so he stays inside because it is too dark out there. He picks up the remote to his TV. When he finds the channel, he wants he slides the remote to the other side of the couch. Something strange happens! The remote keeps going at the same speed until it hits the couch, which stops it. This happens because Newton’s 1st law of motion states that objects will continue to move at the same speed until something stops it, usually friction or air resistance. For this to be observed the conditions must be ideal. In this case, you must be in a frictionless environment, Billy’s discovery must be in a universe in which there is no friction. The remote went on until it hit the couch because the ideal conditions were met and there was nothing slowing it down, like friction, until it stopped when it hit the couch. Objects with more mass want to continue what they are doing more so it is harder to turn or stop an object with more mass. Billy is confused but decides to continue with his exploration of the house.
He finds a light switch he did not see before, so he flips it, but nothing happens. He wants a different chair, so he uses all his force to push the chair into the living room, the chair goes quite quickly. According to Newton’s 2nd law of motion, his force caused the chair to move whereas before there was no force that was greater than any other force that was being acted upon it. Causing it to stay still. He decides to move the couch, which has much more mass to it. When he pushes with the same force he used on the chair, the couch moves slower even though he is using the same force. The reason why the couch is moving slower is because of its higher mass. In Newton’s 2nd law of motion, acceleration of objects is dependent on the mass and net force. Net force is a combination of the force of friction and the force being applied. The force of friction is dependent on the force of gravity, which is based on mass. More mass will equal a higher force of friction meaning that more force is needed to move the object. Since the couch has more mass, its acceleration will be slower as lo ng as the force being acted upon it is the same as the object before it. The higher the mass, the more force needed to move an object at the same speed as one with less mass. The light switch most likely made the universe have friction again, causing the chairs to not continually move. This law is observed when the object has a force acting on it that is greater than any other being applied to it, causing it to move. Forces are balanced when an object is still or moving at a constant rate, an unbalanced force is required to acceleration or move the object slower or faster.
Billy then decides he wants a snack, so he pushes off his chair to get to the kitchen. He moves a bit faster because of this but the chair falls down. This is because of Newton’s 3rd law of motion. The law states that “for every action there is an equal and opposite reaction”. This means that if you push an object the object will push you with the same amount of force. Billy is pushing off of the chair and that pushes the chair backward, but the chair pushes him forward with the same amount of force. For this law to be observed there must be two objects in play. After he gets his snack he realizes he still hasn’t seen his parents in a while, so he starts to get worried. The sun is starting to come back up, he decides to look outside only to find a landscape of black rock as far as the eye could see. He remembers about the light switch, so he flips it. He looks outside to see objects sliding by his house at a constant speed. They start to hit his house and he runs to turn off the switch. It does not seem to do anything this time! He runs to the basement only to find the door now missing. Billy screams in horror as he realizes he is now stuck in a frictionless world forever.