Hi there, The question certainly isn't stupid... In fact it's probably too complex for me to answer with much certainty!
In Physics we like to simplify things as much as possible, and what I see in your question is a conservation of momentum problem. That is, the initial momentum off all objects is equal to the final momentum,
Our initial momentum comes from the bike and the car separately so we add their momenta
Momentum is classically defined as mass*velocity. So what our final equation is going to look like is:
You gave the velocities so lets get some numbers for the masses. We'll take the weight of a Harley Davidson "Forty-Eight"
at about 250 Kg for our bike. And we'll use the weight of a Toyota Camry SE
for our car at about 1500 Kg.
We'll also add 85 kg to the bike and 170 to the car giving them 1 and 2 passengers respectively.
So we have:
=(300Km/h*335Kg +100Km/h*1670Kg)/2005 Kg = 133 Km/h
Now this is a very idealized situation where the two collide and remain joined. Obviously in a real situation things can get much more complicated. The motorcyclist is likely to be thrown off the bike, and it's impossible to know what the driver will do afterwards that may either help or hinder. But if we want some idea, another thing we can look at is the kinetic energy involved.
Again this we add the initial energies and compare to the final.
= 1/2*335*(300^2)+1/2*1670*(100^2)=23425000 Kg(Km/h)2
or about 1.8 megajoules.
=1/2*2005*(133^2) = 17733222.5 Kg(Km/h)2
or about 1.4 megajoules
So we have a difference of 400,000 Joules, but where did it go?
Well that's the "crash." That energy goes into damaging both the car and the motorcycle, into the sound of the accident, and anything else you can think of involved in a vehicular collision.
All I can tell you for sure is that 400,000 joules will run a 100watt incandescent light bulb for about an hour, or that it's the amount of caloric energy in a banana.
I can't really say for sure what gets damaged and how much is done, but if I was forced to pick a side, I'd say the car at least would probably still be drivable after the accident.
Thanks for the question,
(published on 04/19/2012)