Sir Isaac Newton and His Motorcycle Laws
Sir Isaac Newton and Motorcycles: The Laws of Motion and Gravity
Good old Sir Isaac, he must have known long ago that we would eventually adventure forth in motorcycles (and other types of transportation machines as well) and devised a set of Laws that would govern what we could do with our bikes, and lives.
Those 3 little laws that form the Laws of Motion do indeed determine what we can and cannot do while riding, and what manufacturers have to do to make sure we enjoy ourselves.
On the serious side, let's look at Sir Isaac's motorcycle revelations (OK, he did not make them up just for motorcycles, but it makes it more interesting that way). So, here we go.
1. An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
This law is often called "the law of inertia".
How does this effect you and your ride? Pretty simple... The motorcycle will go no where unless you get the wheels moving, and that requires an unbalanced force acting upon it, namely the power that your engine can deliver through the twist of the throttle (remember, I am trying to keep this as simplistic as possible or my head will explode!) As long as we keep the throttle twisted, the bike continues to move at a constant speed, unless other factors come into play to alter that, such as braking action or a deer (been there, don't wish to go there again!)
2. According to Sir Isaac's 2nd Law - Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object). Force equals mass times acceleration. (F=MxA)
Again, the twist of the throttle and the engaging of gears creates that unbalanced force causing the bike to move, and does so according to the 1st Law. However, the power behind that throttle must be able to overcome the tendency for the bike to stay in the same place, at rest. The more massive the bike,the more power from the engine is required in order to "make it go". Knowing this, manufacturers do not make 900 pound motorcycles powered by 50cc engines, and is also why race bikes are designed to be as lean, in terms of mass or weight, and mean, in terms of available power, as they can be. Following the formula, According to the 2nd law, a Lighter bike = less power needed to make it move, and if you apply great amounts of power, well, wahoo! Also keep in mind that the more weight you pack onto your bike (you, passenger, saddle bags / panniers, "stuff"), the more force is needed to make it operate as normal, and the more force is also needed to bring it back to rest. What does this mean? Longer acceleration times to get up to speed, and greater deceleration times to get back to rest.
3. The 3rd Law goes something like this: For every action, there is an equal and opposite re-action.
If you accelerate to a certain speed, it also requires a certain amount of force equal to that acceleration to bring you to a stop (factor in the use of friction). As well, if you come in contact with another object, usually one not as desirable as a long lost friend, it has a tendency to push back with the same amount, or equal re-action as to how you came into contact with it. We sometimes call this the "Oh s--t factor! This law is the one that really hurts the most. If you have not had the opportunity to experience it for yourself, those of us who have this experience under our belts (or ribs, or head, or...) try as best you can to avoid it. Not having a story to tell in this case is a good story in itself.
4. The Force of gravity between two objects depends on the mass of each object and the distances between them, and the greater the masses of each object, the greater the gravitational force between said objects.
Well, what can you say about gravity? A lot! If you let go of your motorcycle (other than the three wheeled type), and the side stand or centre stand are in the "neutral" position, the bike has a tendency to fall over. Funny about that. As long as the other laws (1 to 3 are working), the bike does not fall over until we get back to rest, and forget to put the side stand down before getting off. When this happens, we have to quickly come up with an excuse as to why we let the bike fall over as we were dismounting ("I got a muscle spasm in my leg", "I put the side stand down but it must have malfunctioned like Janet Jackson's dress at the Super Bowl", "I just had a momentary lapse of judgement based on too much stuff floating around in my head", etc.). You have probably heard them all, or may even contributed to "the excuse".
If the bike, and you, are more massive, the greater the attraction with the ground or another object, and the more they want to come together. Cue Law #3. In our motorcycle training classes, we continually tell our students that if the bike is on its way over to be parallel with the pavement, let it go! Do not try to save it. Save yourself. The parts of the bike are easier to replace than your parts.
Putting all these Laws together allow us to ride our bikes safely, whether just cruising around, or out on the MotoGP. The task we have is to make sure we respect them and keep the unpleasantries they can create if not respected out of our rides.