You may have heard the story of an apple falling on Sir Isaac Newton’s head that led him to discover the 3 famous laws of motion, inventing calculus along the way to describe them (and haunting high school students with two difficult subjects to this day):
- Law 1: An object will continue its current path if there is no net external force acting on it. Note that a force is a vector and has a direction and a magnitude. The key here is the word ‘net,’ which is the sum total of all the external forces combined. A cup seemingly resting on a table not moving is in fact having two opposite forces acting on it that cancels each other out – its weight pulling it down and the force from the table supporting it. Or a piece of debris in space (or Sandra Bullock in the movie Gravity) when, without gravity’s pull, will continue to travel into outer space at the same speed in the same direction (forever).
- Law 2: The acceleration (or how fast the velocity changes) of an object is directly proportional to the net external force acting on it, and inversely proportional to the mass of the object. Again, it is the ‘net’ force that is the key. For example, the larger the horse power of a car, the faster the car can be propelled up the freeway on-ramp. And for the same engine, the heavier the car, the slower the acceleration.
- Law 3: For every force acting on an object, the object will push back with an equal but opposite force. This is similar to law 1, like the cup’s weight pushing down on the table, the table in turn pushes back up to the cup with a force equal to the cup’s weight but in the opposite upward direction. The difference between law 3 and law 1 is that these 2 forces are from 2 different things – the cup and the table, while in law 1 we are talking about all the forces combined to act on the cup.
The beauty of Newton’s Laws is that they can 100% predict the locations and velocities of all objects given their masses and interacting forces. In other words, using Newton’s Laws, we can definitively find out where an object comes from and where it will end up at any time.
In life, wouldn’t you want to know where you are going? Using the same concepts in Newton’s Laws, you can also predict quite accurately where your life will end up. Here are the 3 Newton’s Laws for Living: