According to Newton's first law, an object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. It is the natural tendency of objects to keep on doing what they are doing. All objects resist changes in their state of motion. In the absence of an unbalanced force, an object in motion will maintain this state of motion. This is often called the law of inertia. The law of inertia is most commonly experienced when riding on the roadways. In fact, the tendency of moving objects to continue in motion is a common cause of a variety of transportation injuries - of both small and large magnitudes. Consider for instance the unfortunate collision of a motorcycle with a wall (or any obstacle inints path). Upon contact with the wall, an unbalanced force acts upon the motorcycle to abruptly decelerate it to rest. The rider of the motorcycle would also be decelerated to rest if strapped to the motorcycle by seat belts or some form of safety harness (which is not necessarily a good idea - please read on!).

Being strapped tightly to the motorcycle, the driver would always share the same state of motion as the motorcycle. As the motorcycle accelerates, the rider accelerates with it. As the motorcycle decelerates, the rider decelerates with it. And as the motorcycle maintains a constant speed, the driver maintains a constant speed as well. But what would happen if the rider were not wearing the seat belt? What motion would the rider undergo if she/he failed to use a seat belt and the motorcycle were brought to a sudden and abrupt halt by a collision with a wall or any other obstacle in its path? Were this scenario to occur, the driver would no longer share the same state of motion as the motorcycle. If a seat belt were used on a motorcycle, then the forces necessary for accelerated and decelerated motion would exist. Without a seat belt, the rider is more likely to maintain its state of motion. The animation below depicts this scenario. If the motorcycle were to abruptly stop, then the rider in motion would continue in motion.

The rider would likely be propelled from the motorcycle and be hurled into the air. Once they leave the motorcycle, the rider becomes a projectile and continues in projectile-like motion. But why then are motorcycles not equipped with safety harnesses? Is this a gross oversight made by motorcycle manufacturers? While no transportation accident is safe, it is the goal of the manufacturers of all roadway vehicles to produce a vehicle which maximizes the safety of its riders. best trickle charger for a motorcycleIn the case of a motorcycle, it is believed that the rider's safety is maximized by not strapping the rider to the motorcycle. motorcycle dealer in concord nhIn a car accident, the safest place to be is in the car; nankang tires for motorcycle

yet in a motorcycle accident, the worst place to be is on the motorcycle. Cars are four-wheeled vehicles which have a stable platform capable of resisting sideways motion and resisting tipping over. As such, being strapped to the a car in an accident is an advantageous strategy for maximizing passenger safety. On the other hand, a motorcycle is a single-track vehicle (two wheels) which are prone to tipping over and sliding into and underneath the obstacles which they hit. motorcycles for sale in overland park ksImagine being strapped to your motorcycle as you slide underneath a 2000-pound car. uganda law on motorcycle helmetsBeing strapped to the motorcycle by a safety harness, you would share the fate of the motorcycle itself - being crushed by the 2000-pound car. motorcycle shop atoka ok

Your chance of survival would be minimal. On the other hand, if you were to leave the motorcycle and be flung into the air, it is more likely that your hopeful impact with the ground would slowly alter your velocity as you skid to a stop over a lengthened period of time. Motorcycles are inherently dangerous vehicles; yet like all vehicles, manufacturers design them in a manner that maximizes rider safety. motorcycle shop yuba cityThe omission of safety harnesses from motorcycles means that the motorcyclist does not share the same fate as the tipped over and skidding single-track vehicle. For more information on physical descriptions of motion, visit The Physics Classroom Tutorial. Detailed information is available there on the following topics: Return to List of AnimationsHelmet and acoustics research might offer riders a quieter trip.Before hopping on his motorcycle, Michael Carley puts on earplugs, followed by his helmet.

It's a step many riders take. After accelerating, most of the sound that a rider can hear isn't from the bike engine or other vehicles on the road, but from the air rushing over and around his helmet.The helmet Carley wears is designed and tested for comfort and impact protection -- but not for sound protection. Noise inside the helmet can reach rock-concert levels when traveling at highway speeds.Carley, a mechanical engineer, has gathered a group of engineers and psychologists to study how to minimize helmet noise. The group includes researchers from two U.K. universities, the University of Bath, where Carley works, and nearby Bath Spa University. They are studying how to protect riders from hearing damage and reduce the potential distraction that noise poses to riders."Riding a motorcycle is a very noisy endeavor," said Rick Korchak, editor of webBikeWorld, a popular motorcycle website that carries detailed helmet reviews. "There are no quiet motorcycles and there are no quiet helmets."

While riders and others recognize that noise can be a problem, many U.S. jurisdictions prohibit the use of earplugs or other noise-reducinging devices. One long road trip could take a rider through numerous changes in local laws."A lot of people, they just do what they're comfortable with, irrespective of what the jurisdiction says is the law," said Charles Brown, a psychologist specializing in sound perception from the University of South Alabama in Mobile."We strongly advocate the use of high-quality, correctly inserted ear plugs when riding a motorcycle," said Korchak. He added that good ear plugs will not eliminate all noises, allowing sirens and traffic to be heard.Sound ResearchRiders experience noise from multiple sources.First is the engine noise, which is a relatively insignificant factor once riders accelerate to highway speeds. Audible wind noise can reach volumes as high as 115 decibels or more, roughly equivalent to what power saw operators without ear protection would hear.

The Occupational Safety and Health Administration recommends limiting such exposure to 15 minutes or less per day.Most initial academic research in motorcycle sound focused on long term hearing damage. The group from Bath began researching the topic by establishing reliable measurements of what happens to air passing over a helmet in a wind tunnel. Then, on roads and test tracks, they studied the relative placement of the rider and the motorcycle. They studied how all the important variables interact, such as the height of the windshield, the location of the helmet and the size of the rider.Turbulent air buffeting off the motorcycle windshield is one problem. The researchers found that small differences in air flow patterns can cause large variations in sound level. Subsequently, the Bath group took their experiments to wind tunnels to measure in detail what riders experience.The Bath group's most recent paper, accepted for publication by The Journal of the Acoustical Society of America, details the way airflow around the helmet creates noise.

They found that for the type of helmets with a full shield and visor covering the face, the largest component of noise comes from air rushing around the chin bar, which wraps around the jaw.There's another type of sound experienced by riders, but it's more difficult to quantify, and not affected by earplugs. It's called body conducted sound. Aboard a motorcycle, this process transmits engine vibrations and the percussive force of the wind through the flesh and bone to the ear. Earplugs don't stop it, and it can be significant."It's why your voice sounds different when you hear a recording of your voice versus what you experience as your own voice," said Carley.Limiting Sound's ImpactReducing the amount of sound that reaches riders can benefit more than motorcyclists' hearing. Riders have to process the sound of riding, the sound conducted through their bones, and a wide variety of visual stimuli as well, all while responding to the situation around them.Another topic under investigation by the Bath group is how sound impacts attention.

Nigel Holt, a member of that team and a psychologist at Bath Spa University, said that one experiment measured how different volumes of sound impaired a test subject's peripheral vision.Cutting down the amount of sound reaching riders is a complicated task."Bone and body transmitted sound bypasses the ear canal entirely," said Holt.The Bath group found that lower frequency sounds, including body conducted sound, travel efficiently through the body. The researchers found that a helmet's structure may actually amplify that noise.Helmet designers are primarily focusing on designs that will best protect the head against impact, said John Kennedy, an engineer at the University of Bath. "I suppose the acoustic performance of the linings and the various materials doesn't necessarily enter into the design process."The shape of helmets could be changed to become more aerodynamic and therefore quieter, but a sleek, sweeping wedge like a racing bicycling helmet might fail to match the current shapes for impact protection and also make it more difficult to hold the head steady when peering over the shoulder before changing lanes.

Both the Bath group and Brown believe consistent sound rating standards for helmets are needed and that other systems should be developed to reduce the amount of noise that reaches riders. That might require new research on materials that both protect against impact and limit the transmission of acoustic signals.Brown, working with Michael Gordon, a psychologist at William Patterson University in Wayne, N.J., performed an experiment to see how much noise canceling technology could diminish noise on a motorcycle. These devices produce frequencies that interfere with incoming noise so that the wearer is protected from potentially damaging sound levels.They attached a large set of noise-canceling earmuffs to a motorcycle helmet and placed the assembly atop an acoustically engineered dummy head. Their helmet covered the top and back of the head, but did not have a face shield. After driving the rig around at different speeds, they found that the device reduced sound by as much as 26 decibels, roughly equivalent to the difference in sound between a normal conversation and a busy roadway.

A Fit for the FutureEven without earplugs or noise-canceling, riders can make many minor adjustments to substantially reduce the amount of sound to which they are exposed.Kennedy said that small movements in riding position can change the volume of sound by more than 10 decibels, and that wearing a scarf around the neck can seal off the cavity around aerodynamically-tricky chin bar."The most important thing that motorcycle owners can do is to make sure their helmet fits their head shape," said Korchak.Korchak said that there are five general helmet shapes. Getting the right size and right shape is important, so that the helmet fits snugly around the head and neck, along with jacket collars and the part of the helmet that fits around the neck.Carley said that it’s important that helmets be well-ventilated, so that riders travel with the visor closed. Riding with an open visor can create additional wind noise. He also believes that a change in motorcycle design could help, such as building windshields that allow air to flow through them.