How Seat Belts Help Prevent Fatalities in Road Traffic Accidents

The issue

In America, one of the leading causes of death is motor vehicle crashes. According to many studies, seatbelts have been found to be the most effective way to prevent deaths in car accidents. They have been proven to save many lives of people who wear them and can determine the severity of their injuries. This means that if you do not wear your seatbelt, it is highly likely that the injuries will be much more severe and may result in death. Although many people are aware that not wearing a seatbelt lowers their safety and may result in the death of them or the passengers, studies show that 1 in 7 people still do not wear a seatbelt while driving. A study from 2009 shows that car crashes have taken 33, 000 people's lives and caused 2. 2 million injuries in that year alone. 70% of all crashes involve cars and trucks and 53% of deaths caused by the accidents are because of people not wearing a seatbelt. Results show that in 2009, 90 or more people were killed every day due to motor vehicle crashes.

Solution

As a solution to this issue, Laws have been placed to help increase the number of people using seat belts and save many more lives. It has also risen from the help of technology and the education on how and why to use a seat belt. Studies show that by using these techniques to try and increase seat belt usage, it has worked because it has risen from 11% in 1981 to an estimate of 85% in 2010. According to the CDC (Centers for Disease Control and Prevention), well-enforced and effective seatbelt laws will make certain that everyone who is in a car will use a seat belt every time. The laws that have been placed are the ‘Primary Enforcement laws’ and the ‘Enhanced Enforcement laws’. The science Newtonian mechanics consists of three laws and can be used to describe how seat belts are effective in improving the safety of cars. Newton’s first law is the ‘law of inertia’, which states that ‘an object in motion continues with the same speed and the same direction unless acted upon by an unbalanced force. ’This law describes, how when a car comes to a sudden halt, the passengers inside are thrown forward as the person's body continues to move in the direction the car was travelling. As well as this, the larger the body mass, the greater the inertia. Newton’s second law which is the law of force and acceleration (defined as F=ma) says that when forces that are acting on a body do not balance, then there will be a change in motion. This law describes when a car crashes into something such as a wall, it will come to a sudden stop. The car is effectively going from whichever speed it was travelling at, to zero, as soon as it hits the wall. As for Newton’s third law, this states that ‘for every action, there is an equal and opposite reaction’. This explains the effects of the crash where the kinetic energy is transferred as a result of the crash and the effects it has.

In a crash, there is a loss of kinetic energy. The kinetic energy is dissipated and lost through heat energy when the brakes are applied and sound energy as the noise of the crash. Energy is also absorbed by the car which causes it to “crumple”. However, some energy is also transferred through the body of the passenger resulting in an impact on the body. To help with the dissipation of kinetic energy, seatbelts were designed to help overcome inertia on the passengers and distribute the energy to the car and minimises injury to the passenger. The way in which a seatbelt works is in the system, it contains a webbing that is attached to a retractor mechanism. In the centre of the retractor, there is a spool that is connected to a single end of the webbing. Inside the mechanism, the spring causes a rotation force on the spool that rotates and winds up the loose webbing and will also wind counterclockwise to loosen the webbing. The spring will want to return to its original shape so it resists the twisting motion.

Effectiveness

In 1984, a study was carried out in the USA by the National Highway Traffic Safety Authority. The results found were that three-point seat belts were 40%-50% effective at lowering the number of fatal injuries, 45%-55% effective at lowering serious injuries and 10% effective at preventing minor injuries. It also included that belts only secured at the lap were less effective than the three-point belts. The NHTSA also compared the results with the estimates from eleven different countries. The average percentage of effectiveness for the eleven other countries came to 47. 1%.