LOOK.. ZOMBIES!
lawless heathen .. i bet you ride in jandals and a tshirt too??..Originally Posted by nallac
i swear you youngsters these days with your loud rock and roll and video game parlors and MePods
100 kph is fast enough for anyone .. too fast if ya ask me ...
you should obey all the laws set down by the gubmint .. they know best and are only looking out for us ..
sorry ... i tried so hard to keep a straight face when i typed that .. i think i wee'd a little ..
$1,101,806
There were too many Tui's moments in the last 301 posts to count...
I could talk the legs of a Donkey when I get going but I reckon you lot could convince it to go for a walk afterwards...
Hardcore Biker
Is that it? are we done? Please say we are...this is sooooo repetitious.
Even if I told you all EXACTLY what happened, I doubt if anyone would be at all interested...seems a good old argument is what peeps on this thread want.
NZ Highway Patrol's Road Safety Campaign....
Get Bikes off the Road at All Costs!
Better Red then Dead...
please tell... we are interestedIs that it? are we done? Please say we are...this is sooooo repetitious.
Even if I told you all EXACTLY what happened, I doubt if anyone would be at all interested...seems a good old argument is what peeps on this thread want.
Forum whore
You are completely wrong.
Kinetic Energy of a moving object = 0.5 * mass * velocity^2
In other words, if you travel at twice the speed then you have four times the kinetic energy.
Let's look at the numbers in your example:
E_k of car = 0.5 * 1,000 (kg) * [26.39 (m/s)]^2 = 348 kJ
E_k of bike = 0.5 * 200 (kg) * [58.61 (m/s)]^2 = 344 kJ
In other words both vehicles have exactly the same amount of energy at impact, and will cause exactly the same amount of damage.
The greatest pleasure of my recent life has been speed on the road. . . . I lose detail at even moderate speed but gain comprehension. . . . I could write for hours on the lustfulness of moving swiftly.
--T.E. Lawrence (of Arabia)
Better Red then Dead...
so if the car was loaded up 2000kg then there would be a difference of????
what about a 4500kg camper????
Homo Sapiens Vulgaris
It's quite rich that you who haven't learned - or maybe simply didn't bother - to read in the first place is claiming what I posted is wrong.You are completely wrong.
Kinetic Energy of a moving object = 0.5 * mass * velocity^2
In other words, if you travel at twice the speed then you have four times the kinetic energy.
Let's look at the numbers in your example:
E_k of car = 0.5 * 1,000 (kg) * [26.39 (m/s)]^2 = 348 kJ
E_k of bike = 0.5 * 200 (kg) * [58.61 (m/s)]^2 = 344 kJ
In other words both vehicles have exactly the same amount of energy at impact, and will cause exactly the same amount of damage.
I didn't mention energy - I mentioned momentum (equal to the product of velocity and mass). If you want to analyse an impact you will consider the momentum of the involved vehicles. Both momentum and energy are conserved enterties - however energy can dissipate in many different ways: heat, deformation, etc. Momentum however does not dissipate in that manner. This means it is easy to calculate the change of momentum experienced by either party in a collision. Since force is equal to the time-derivative of momentum (F = dp/dt) you can calculate the force excerted during the collision if you can estimate the time that the collision took. And force is what will break your bones and burst your arteries and internal organs.
Once you have established the change in momentum you can then estimate what energy was absorbed as deformation of the vehicles using the conservation of energy. The more the better - it means that the impact took longer time and so the forces involved would have been lower.
If you are in your car you WILL prefer to be hit by a motorcycle at 211 km/h compared to a car at 95 km/h. (The point of impact and other circumstances being the same). If you are travelling in a car (1000 kg) at 100 km/h and have a frontal collision with a bike (200 kg) travelling at 200 km/h you will continue travelling forward at 50 km/h. If you have a collision with another car (1000 kg) travelling at 100 km/h you will come to a complete stop - what do YOU think will hurt the most?
[nerd part]
Conservation of momentum - assuming the vehicles "stick" after the collision. m and v are the mass and velocity of vehicle 1 and M and V are the mass and velocity of vehicle 2 - v' is the velocity of the "compound" body following the impact.
mv + MV = (m+M)v' <=> v' = (mv+MV)/(m+M)
Vehicle 1: m = 200 kg, v = -200 km/h (negative since direction is opposite to vehicle 2).
Vehicle 2: M = 1000 kg, V = 100 km/h.
v' = (200 kg * -200 km/h + 1000 kg * 100 km/h)/(200 kg + 1000 kg) = (60000 kg*km/h)/(1200 kg) = 50 km/h
It is preferential to refrain from the utilisation of grandiose verbiage in the circumstance that your intellectualisation can be expressed using comparatively simplistic lexicological entities. (...such as the word fuck.)
Remember your humanity, and forget the rest. - Joseph Rotblat
Born to be mild
Good work that man! I would add that all that kenetic energy is going to be concentrated in a smaller area too instead of being spread out as it would be by a car so if you happen to be behind that point of impact it's not going to be good(I'm sure we all remember that old photo of the sports-bike embedded in a wee nana car from Europe somewhere?)To my simple mind I think that if you are the guy pulling out of a side-road there's not going to be too much difference being hit by a 1000kg at 100kph or a 200kg vehicle at 200kph. He's probably going to be just as dead.
Intereresting analogy just ocurred to me. Would you rather be hit on the head by a full swung carpenter's hammer or by a half swung sledgehammer?
Grow older but never grow up
Highway Biker
Cummon! we've all done it before. wrong place, wrong time
Constantly consuming, conquer and devour.
Better Red then Dead...
all went over my head
Homo Sapiens Vulgaris
Making flawed conclusions and calculating the kinetic energy of two moving bodies.
Consider a .50 BMG round (~50 g, ~900 m/s) and an elephant trundling along (3000 kg, 13 km/h) - they have about the same kinetic energy (~20 kJ) and I'm not going to argue which is more deadly. But could you please tell me which of them would be better at moving a heavy body (e.g. a car) when they collide with it?
It is preferential to refrain from the utilisation of grandiose verbiage in the circumstance that your intellectualisation can be expressed using comparatively simplistic lexicological entities. (...such as the word fuck.)
Remember your humanity, and forget the rest. - Joseph Rotblat
Forum whore
Yes the momentum is conserved.
However you have redefined your argument (which is a common rhetorical trick).
In your original post you made absolutely no reference to what kind of vehicle the observer was traveling in, and then in your reply you have suddenly specified that the observer is traveling in a car.
Why is the observer in a car? Why not another motorcycle, a bicycle, or a bus?
My point was valid. Using the numbers you provided in your example, the speeding motorcycle and the non-speeding car each have the same kinetic energy.
The greatest pleasure of my recent life has been speed on the road. . . . I lose detail at even moderate speed but gain comprehension. . . . I could write for hours on the lustfulness of moving swiftly.
--T.E. Lawrence (of Arabia)
Homo Sapiens Vulgaris
Not a trick, where did I redefine anything? I may have been vague - although not by intent, more likely laziness.
If you are on a bike I probably wouldn't bother even looking at the numbers, with any likelihood you'd be in a sorry state indeed.
The reason for putting the observer in the car is more to do with the argument being about putting other road-users at risk - most road-users are in cars.
It is preferential to refrain from the utilisation of grandiose verbiage in the circumstance that your intellectualisation can be expressed using comparatively simplistic lexicological entities. (...such as the word fuck.)
Remember your humanity, and forget the rest. - Joseph Rotblat
Forum whore
I used the numbers that he provided in his example.
If you want to consider the kinetic energy of larger vehicles, then the numbers will of course be different.
The greatest pleasure of my recent life has been speed on the road. . . . I lose detail at even moderate speed but gain comprehension. . . . I could write for hours on the lustfulness of moving swiftly.
--T.E. Lawrence (of Arabia)
Forum whore
No drama.Not a trick, where did I redefine anything? I may have been vague - although not by intent, more likely laziness.
If you are on a bike I probably wouldn't bother even looking at the numbers, with any likelihood you'd be in a sorry state indeed.
The reason for putting the observer in the car is more to do with the argument being about putting other road-users at risk - most road-users are in cars.
My point was only that introducing a discussion of momentum only makes sense if you know the specific masses and velocities of both parties that are involved in the collision.
If you don't know the masses and velocities of the colliding vehicles then you cannot draw a general conclusion.
The greatest pleasure of my recent life has been speed on the road. . . . I lose detail at even moderate speed but gain comprehension. . . . I could write for hours on the lustfulness of moving swiftly.
--T.E. Lawrence (of Arabia)
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