The image distance always equals the object distance. The size of the image is the same as the object (the mirror does not magnify the image). Coba gambarnya di klik!!
Reflection from Convex Mirror
The image produced by a convex mirror is always virtual, and located behind the mirror. When the object is far away from the mirror the image is upright and located at the focal point. As the object approaches the mirror the image also approaches the mirror and grows until its height equals that of the object.
Reflection from a Concave Mirror
When the object is far from the mirror, the image is inverted and at the focal point. The image is real light rays actually focus at the image location). As the object moves towards the mirror the image location moves further away from the mirror and the image size grows (but the image is still inverted). When the object is that the focal point, the image is at infinity. As the object moves towards the mirror inside the focal point the image becomes virtual and upright behind the mirror. Initially the virtual image is much larger than the object and really far away, but as the object approaches the mirror the virtual image also approaches the mirror and decreases in size.
Sumber :kettering.eduKelembaman
Newton pernah bilang( di hukumnya yang kedua), sebuah benda bergerak terus-terusan dengan kecepatan tetap dan arahnya juga sama, kecuali kalo ke benda itu dikasih gaya yang ngga seimbang. Kondisi ini boleh jadi menjadi kecenderungan dari benda untuk tetap bekerja pada pekerjaannya tsb. Semua benda akan bertahan pada posisi geraknya. Kalo ngga ada gaya yang seimbang, benda yg bergerak...ya tetap bergerak ajach. Ini sering disebut hukum inersia.
Hukum inersia ini sering kejadian di jalan raya. Kenyataannya, kecenderungan benda yang bergerak untuk terus bergerak- adalah penyebab umum kecelakaan lalu lintas, baik fatal atau yang biasa ajach. Coba perhatikan tabrakan antara sepeda motor dengan tembok, klik gambar di atas- seru ya...., tapi jangan dipraktekkan....Disaat orang tsb menabrak tembok, gaya yang tidak seimbang bekerja pada motor, sehingga motor mengalami perlambatan sampai berhenti. Yang nyupirnya juga mengalami perlambatan sampai berhenti, ya celaka..begitu,mungkin bisa menjadi almarhum. Makanya polisi menyarankan kita untuk menggunakan helm. Atau kalo naik mobil perlu ikat pinggang pengaman.
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 deccelerates, the rider deccelerates 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 deccelerated 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 motorcyle manufacturers? Absolutely not! 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. In the case of a motorcyle, it is believed that the rider's saftey is maximized by not strapping the rider to the motorcycle. In a car accident, the safest place to be is in the car; yet in a motorcycle accident, the worst place to be is on the motorcycle. The reason? 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. Imagine being strapped to your motorcyle as you slide underneath a 2000-pound Buick. Being strapped to the motorcyle by a safety harness, you would share the fate of the motorcycle itself - being crushed by the 2000-pound Buick. 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. The 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.
0 komentar:
Posting Komentar