# Determine speed of car from result of impact?

• doggonemess
In summary, the conversation discusses the possibility of calculating the velocity of a car involved in an accident based on the data available. However, it is stated that accident reconstruction is a complicated process and it is not possible to accurately calculate the velocity without professional help. The person involved in the accident is curious about the speed of the other car and is willing to make some assumptions to get a rough estimate.
doggonemess
Greetings,

It's been quite a while since I had to do anything with velocity, friction, mass, and practically any physics over simple calculations. My car was hit yesterday while parked. There were no injuries, and it still drives just fine. The collision was hard enough to deploy the other car's airbag.

I don't need to know the answer for legal reasons, it's all being taken care of by insurance. But out of curiosity, is there a way to calculate the velocity of the car from the data that I have?

I can tell from how offset my car is from straight how much it moved. I know the masses of both vehicles, as well as the road surface where my car was sitting for the friction of the tires.

Can someone noodle this one out? I'd love to know.

Jamie

doggonemess said:
is there a way to calculate the velocity of the car from the data that I have?
No. Accident reconstruction is a very tricky business. Of course you can do some idealised setup where you can input what you know, but it will not be very accurate.

Orodruin said:
No. Accident reconstruction is a very tricky business. Of course you can do some idealised setup where you can input what you know, but it will not be very accurate.

I'm happy with making some assumptions and getting a ballpark figure. I suspect they were going faster than 25 mph due to the airbag deployment. I'm wondering if they were going much faster than that.

doggonemess said:
Greetings,

It's been quite a while since I had to do anything with velocity, friction, mass, and practically any physics over simple calculations. My car was hit yesterday while parked. There were no injuries, and it still drives just fine. The collision was hard enough to deploy the other car's airbag.

I don't need to know the answer for legal reasons, it's all being taken care of by insurance. But out of curiosity, is there a way to calculate the velocity of the car from the data that I have?

I can tell from how offset my car is from straight how much it moved. I know the masses of both vehicles, as well as the road surface where my car was sitting for the friction of the tires.

Can someone noodle this one out? I'd love to know.

Jamie
As already pointed out, we do not help with accident analysis and reconstruction here. Please consider hiring a specialist to help you with this.

## 1. What is the formula for determining the speed of a car from the result of an impact?

The formula for determining the speed of a car from the result of an impact is: speed = (2 x distance)/time. This formula is based on the principle of conservation of energy and can be used to calculate the initial speed of a car before the impact occurred.

## 2. How do you measure the distance of the impact?

The distance of the impact can be measured by using various methods such as measuring tire marks, analyzing the damage to the vehicles involved, or using specialized equipment like laser measurement devices. It is important to accurately measure the distance as it directly affects the calculation of the car's speed.

## 3. Can the speed of the car be determined if there was no impact?

No, the speed of the car cannot be determined if there was no impact. The formula for determining speed from an impact relies on the fact that there was a change in energy due to the collision. Without an impact, there is no change in energy and therefore the speed cannot be calculated.

## 4. How does the weight of the car affect the speed calculation?

The weight of the car does not directly affect the speed calculation. However, it can indirectly affect the distance of the impact. A heavier car will typically cause more damage upon impact, resulting in a larger distance measurement and therefore a higher calculated speed.

## 5. Is it possible to determine the speed of a car from an impact if there were multiple vehicles involved?

Yes, it is possible to determine the speed of a car from an impact involving multiple vehicles. The same formula can be used, but the distance measurement will need to take into account the combined distance traveled by all vehicles involved. It may also be necessary to consider the different weights and speeds of each vehicle in the calculation.

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