# Motorcycle Crash

1. Oct 6, 2005

### Bryan_CT

Hi All. Sorry if I am bugging but I have a question. I am not a physics person but would like to see if someone can do some quick math for me.

Then if anyone wants to...
A motorcycle weighing approx 425lbs traveling @ 155mph with a 180lb rider, How much energy would the total object be carrying when it ran into the car (probably about 1800-2300lbs)

Thanks!

Last edited by a moderator: May 2, 2017
2. Oct 6, 2005

### TOKAMAK

425 pounds ---> about 200 kg, if we add the driver that's about 290 kg, 155 mph ---> about 70 m/s, so the kinetic energy is 1/2 mv^2 ---> ~ 95,550 joules. What units do you want? Joules? Calories? Btu's? Kilowatt-hours?

3. Oct 6, 2005

4. Oct 7, 2005

### HallsofIvy

No, unfortunately we CAN'T give you the energy in units of "kilograms of force" any more than we could give it to you in "meters of time"!

In the first place, energy is not "force", and in the second, you don't measure either force or energy in "kilograms".

5. Oct 7, 2005

### krab

Tokamak: I get 700,000 joules.

Notice the motorcycle stopped in about 2 metres (we ignore the fact that the car was pushed over). So the average force of impact was about 350,000 newtons, which is about 80,000 pounds. It is no wonder the motorcycle ripped right through the car's steel frame.

I don't have a lot of sympathy for the driver, but he killed 2 other people. A real tragedy. Making bikes like these available to new drivers is like letting kids fool around with loaded guns.

6. Oct 8, 2005

### Bryan_CT

hallsofivy. I'M talking about how much the force object would have. Like the muzzle energy of a gun. I think krab answered it.

In the first place I said i diddnt understand physics, and the second in over 6000 posts I would think you could help, insted of telling me how wrong I am.

"For a list of ways technology has helped improve modern living... please press 1 now."

Last edited: Oct 8, 2005
7. Oct 8, 2005

### Pengwuino

Objects don't have force. They exert forces on other objects. The muzzle of a gun doesn't have a force either. What happen in a gun is an explosion. The explosion (or more specifically, the expansion of gases) EXERTS a tremendous pressure (force) on the bullet which expels the bullet out of the muzzle.

In this case, the motorcycle exerts a force on the car. In this real world situation, the "force" was basically exerted via the crumpling of a large amount of steel.

8. Oct 8, 2005

### Tide

Bryan,

Halls was helping. Whether it's Physics or any other discipline language is important and you will remain confused if you do not learn and use the terminology correctly and accurately. After 3 posts you should thank him! :)

9. Oct 8, 2005

### Bryan_CT

ok, i think i am being misunderstood.

If an object carrying x ammount of mass is in motion,
will the "theoretical mass" of the object be increased as the rate of motion is increased

ie. will an object weighing 10kg moving at 10kps
have the same 'theoretical mass' as an object weighing 100kg moving at 1kps, when it impacts another object (for arguements sake, lets say any soild 'unmoveable (realitive to the object in motion) object'

Im am using what you guys are explaining as 'energy' and tanslateing it into 'theoretical mass of an object upon impact' If that is possible, or maybe I am the misunderstood. It might be what I am talking about is 'theoretical', because the actual measurement used in this case is 'energy' ie. joules

My point with hallsofivy is this...
If you can explain to me how I am misunderstood, why not just skip the misunderstanding and get right to the solution? If you can tell me how I am wrong, why not then enlighten me.

Bryan