About cars - safety
Road traffic accidents are the largest cause of injury-related deaths worldwide.6 Mary Ward became one of the first documented car fatalities in 1869 in Parsonstown, Ireland,43 and Henry Bliss one of the United States' first pedestrian car casualties in 1899 in New York City.44 There are now standard tests for safety in new cars, such as the EuroNCAP and the US NCAP tests,45 and insurance-industry-backed tests by the Insurance Institute for Highway Safety (IIHS).46
Worldwide, road traffic is becoming ever safer, in part due to efforts by the government to implement safety features in cars (e.g., seat belts, air bags, etc.), reduce unsafe driving practices (e.g., speeding, drinking and driving and texting and driving) and make road design more safe by adding features such as speed bumps, which reduce vehicle speed, and roundabouts, which reduce the likelihood of a head-on-collision (as compared with an intersection).
Main article: 2-stroke engine
The defining characteristic of this kind of engine is that each piston completes a cycle every crankshaft revolution. The 4 processes of intake, compression, power and exhaust take place in only 2 strokes so that it is not possible to dedicate a stroke exclusively for each of them. Starting at TDC the cycle consist of:
Power: While the piston is descending the combustion gases perform work on it?as in a 4-stroke engine?. The same thermodynamic considerations about the expansion apply.
Scavenging: Around 75° of crankshaft rotation before BDC the exhaust valve or port opens, and blowdown occurs. Shortly thereafter the intake valve or transfer port opens. The incoming charge displaces the remaining combustion gases to the exhaust system and a part of the charge may enter the exhaust system as well. The piston reaches BDC and reverses direction. After the piston has traveled a short distance upwards into the cylinder the exhaust valve or port closes; shortly the intake valve or transfer port closes as well.
Compression: With both intake and exhaust closed the piston continues moving upwards compressing the charge and performing a work on it. As in the case of a 4-stroke engine, ignition starts just before the piston reaches TDC and the same consideration on the thermodynamics of the compression on the charge.
While a 4-stroke engine uses the piston as a positive displacement pump to accomplish scavenging taking 2 of the 4 strokes, a 2-stroke engine uses the last part of the power stroke and the first part of the compression stroke for combined intake and exhaust. The work required to displace the charge and exhaust gases comes from either the crankcase or a separate blower. For scavenging, expulsion of burned gas and entry of fresh mix, two main approaches are described: Loop scavenging, and Uniflow scavenging, SAE news published in the 2010s that 'Loop Scavenging' is better under any circumstance than Uniflow Scavenging.6
Accidents while drunk
Driving after drinking can be dangerous even when guided bike. In the case of more complex machines, allowing to achieve a much higher speed, directing them under the influence of alcohol can be fatal. Despite the many social campaigns regarding the prohibition of driving under the influence of alcohol and strengthen penalties for drunk drivers, unfortunately, many of them still do not apply to this rule. Meanwhile, the management of a car under the influence of alcohol can lead to death of not only the driver and passengers, but also to the disappearance of completely innocent people, not even staying on the road during this event. Getting into the car under the influence of alcohol we create unnecessary risk.