Please help a noob with the following question: A pound motorcycle, traveling at 65 mph crashed into a 3200 pound car, that is traveling, at 15 mph, in the same direction as the motorcycle. What are the physics involved in such a crash and what would be expected to happen to the rider of the motorcylce? What physics are applied to him? Any help would be greatly appreciated. Thank you.
Your question seemed to omit the weight of the motor cycle. Such a question is easy to answer for inelastic collisions (Example: Billiard balls, but difficult otherwise). For a motorcycle & a car (or a rigid wall), some of the energy/momentum would be used in deforming the colliding objects With billiard balls, energy/momentum loss is negligible & can be ignored.
The physics are pretty complicated but can be simplified with some assumptions. But in general, a crash like that would be on the order of you sitting on your bike and riding it off a 3 story building.
I'm not going to do all of your math homework for you. But as a former motorcyclist for many years, I can tell you what will happen to the rider. When a bike runs into a car (or any object) the front suspension is compressed. This facilitates the unweighting of the rear wheel, which lifts off the ground. It does this with so much force that it catapults the rider into the air. Ironically, a high-speed collision of this type often leaves the rider in rather good condition, because he sails right over the top of the car and lands on the ground. He could easily break an arm or something like that (the catapult effect makes him spin so there's no telling which part of him will hit the ground first), but there's a very good chance that he will recover completely. Two of my friends had that experience. One broke a wrist, the other was not seriously injured--although both attributed that to their helmets. But it's much different in collisions where the motorcycle hits the car at high speed. Instead of bouncing off the car, it crashes right through the sheet metal and the glass. It it's a T-bone collision (running into the side of the car), the rider goes right along with it and is almost always killed by the impact--along with the occupants of the car. I saw a Cadillac with a Suzuki completely inside it. Nobody survived.
I KNEW I should have prefaced my question with, "No, this is not a homework question". In all actuality, this is a real world question. This actually happened to me a few months ago. Hoping to get a rough reconstruction of the accident based on the motorcycle debris field after the crash (the distance from the impact to where things ended up, including the rider-i have this info, but I don't want to influence anyone's answer). What I'm hoping to distinguish is the difference between if the car was doing 15 mph and if the car was going 65 mph. The weight of the motorcycle was 400 pounds.
YoMonmmas:The following information should be available: Your local police department should have access to accident investigation data. There is a big difference between a crash speed of 15 & a speed of 65MPH. Crash investigators would at least be able to tell you that it is closer to one speed than the other.
I wish I could afford to pay a crash investigator. I, already, have all of the accident investigation data, what I need is someone that knows how to analyze it, so the crash can be reconstructed to show what speed the car was going at the time of impact. I have details, such as: the distance items (motorcycle, motorcycle gas tank that was disconnected from the bike), how far the car traveled after impact, etc. I'm hoping someone can use the details to figure out the one unknown: how fast the car was moving at impact. Thanks.
