# Calculate the damage of the car after collision

1. Jan 25, 2015

### ali farooq123

I'm developing a 3 Dimensional android car game, so i need a formula to calculate the damage of the car after colliding the tree, wall or signal.
I have velocity and mass of the car and also i have the mass and velocity of the colliding object. I use inelastic collision formula for signal and barrier collision and elastic collision formula for wall and tree, so i need a formula to calculate the damage of the car after collision. Help me thank you waiting for your suggestions.

2. Jan 25, 2015

Staff Emeritus
What are the units of "damage"?

3. Jan 25, 2015

### ali farooq123

i am taking the 100% damage bar for car that will be decrease according to the collisions of the car

4. Jan 25, 2015

### sophiecentaur

I think Vanadium may have been a trifle sarcastic there;) . You are asking a Physics Forum for a formula(?) which will produce a numerical output from Physical input data. What units did you want? If you can tell us the units you want then you might hope for an answer.

Many insurance companies and claimants would love the information that you want, too - to work out speeds etc. before a crash. We get regular questions about it. I think that, like insurance companies, you may have to make it all up.

5. Jan 25, 2015

Staff Emeritus
The point is you want a formula. If I gave you one that says the damage was "6", what have you learned? You need to quantify "damage" before an equation will do any good, and as sophicentaur points out, other people - people with financial interests - have put a lot of effort into this without success.

6. Jan 25, 2015

### ali farooq123

Can u tell me that which damage unit is best for my game because I have see many units like damage per second, terran, zerg, protoss etc.

7. Jan 25, 2015

### davenn

there isn't something called a damage unit

none of those are scientific units ... they are all make believe

8. Jan 25, 2015

### sophiecentaur

9. Jan 26, 2015

### ali farooq123

units of damage are speed and force

10. Jan 26, 2015

### jbriggs444

At best, those are inputs to the damage computation process. They do not qualify as units of damage because, for one thing, they are entirely different things.

11. Jan 26, 2015

### ali farooq123

is it 1/2mv^2 units. i am developing a game in which i have to deal with damage of a car when it collides but i don't know how to do it?
I know the current car speed, its mass. Now the car will collide with a certain non moving object e.g a wall. Now how i calculate the damage of a car at different speeds.

Last edited: Jan 26, 2015
12. Jan 26, 2015

### sophiecentaur

You keep asking the same specific question, despite being told there is no answer. If you really want a definitive answer then buy a number of old cars and run them into walls to see what damage is caused at different speeds. Alternatively, you could research Court records and look at photographs of damaged vehicles. You could then make up your own table of speed, vehicle mass and some arbitrary scale of the damage as you would assess it. There are a number of court cases where expert witnesses have given opinions about likely speeds in accidents and, of course, your assessment could be much more approximate.
In actual fact, your question is a much more reasonable one than the typical "how fast was that car going when it hit me and caused this damage" because there is no Judge and no Money involved and a very approximate answer would suffice. But I think you would need to do your own research on this because it is not in the realms of Physics, I'm afraid. The damage to a passenger is far better documented these days because cars are designed to sustain damage in order to protect the occupants - see what happens to a Formula One car in a crash from which the driver emerges, very much alive swearing at his bad luck in the race. Crumple zones rule these days.

13. Jan 26, 2015

### Creative name

Why not set a limit to catastrophic loss of kinetic energy? You know 1/2mv^2 for each collision, so keep adding it up until you reach a limit you choose. Scale it to 100 (or whatever) and call it done.

14. Jan 26, 2015

### sophiecentaur

How would that number relate to distortion of metal, though? Calculating the KE of a moving car is a trivial exercise. It's predicting the actual Physical effect that's giving him the problem.
What would be your basis for arriving at a limit to choose? (Without arm waving)

15. Jan 26, 2015

### Creative name

I thought he was trying to figure out essentially when the car wouldn't go anymore for the purposes of a game. How bent the car looks is an aesthetic choice you base on how many major collisions a player has had given the number allowed by the developer. I'd allow something like ten hit-a-wall-at-80 type crashes. By about the eighth crash, the car would look pretty bad, but it would be artwork to portray it in an entertaining fashion.

It never occurred to me that video game developers would want to literally translate a change in kinetic energy to a car's appearance. All the calculation required to do that right, assuming you got data from real accidents and such, would use up too much processor time to be useful.

16. Jan 27, 2015

### sophiecentaur

But 'bending' can affect functionality. That was what I was referring to. Sometimes you can't drive home after even a simple collision, if the steering or cooling systems are affected.