# What was the impact force of a truck hitting my car at 35-40 mph?

• Robert Wingate
In summary, the conversation discusses a car accident where the individual was rear ended by a large truck while waiting for the car in front of them to turn left. The accident resulted in damage to both the rear and front of the individual's car, as well as injuries. They are seeking information on the impact force of the collision, but it is difficult to determine due to the complex nature of car collisions and the various factors involved. Insurance claims and expert opinions are often used to determine liability and compensation in these situations.
Robert Wingate
All,

I was rear ended and I would like to know the impact force...

I was waiting for the car in front of me to turn left, so I had my foot on my brake, I was driving a 2004 Lexus RX330...call it 3500 lbs.

A large truck was texting and driving...and without braking ran into the back of me @ 35-40 mph...his truck is 17,000 lbs and he was carrying another 5,000 lbs of deliveries

After the initial rear end crash, then my car was catapulted into the minivan in front of me trying to take a left...my car was totaled from the rear, and the front collision...

Can someone please tell me approximately the impact force that hit me from behind? I am not an engineer, just a guy with a bunch of metal staples and stitches in my head.

Someone, please respond. Thank you very much!

Hi and welcome to PF.
I am afraid that you won't get you want from PF because there is no way of knowing the "impact Force" that you are asking for. PF gets posts like yours very frequently and people are always disappointed by the answers they get.

The first point is that motor car collisions are very complex; they are not like the more straightforward billiard ball collisions that we do in elementary Physics. The second point is very fundamental and that is that collisions are not instantaneous and there are many combinations of Force and the time for which the force is applied that will give the same outcome. There are two quantities that count in collisions and they are Kinetic Energy and Momentum - see, it's getting heavy already.

Motor car manufacturers and road safety labs spend many millions of pounds / dollars etc. in attempts to minimise passenger injury at the expense of the rest of the car being totalled. There is a massive knowledge base and a long history of court cases and insurance claims.
Successful court cases rely on 'expert opinions' about the likely circumstances of car crashes. There is a lot of data about speeds and damage (to cars and to people) and not much of it is indisputable (afaik - because expert witnesses will disagree very often). Photos of tyre skid marks are the best evidence of speed before impact but even those need to be presented by an 'expensive' witness and I don't think any DIY case would be worth the effort.

If you have evidence that the truck driver was texting then you surely have him bang to rights. If the order of the impacts was a rear shunt, followed by your vehicle being pushed into the one in front then he should be liable for all the damage. Otherwise, I think it's normal for insurance companies to divvy up the claims according to their own magical rules and there is seldom much you can do about it (not in the UK, at any rate). The basic rule is that they never pay as much as you think they should and they are bigger than the customer!
Sorry, but I reckon that's the way it is and PF has failed you.

## 1. How do you calculate impact force?

Impact force can be calculated using the formula F = m x a, where F is the force, m is the mass of the object, and a is the acceleration due to the impact.

## 2. What is the unit of measurement for impact force?

The unit of measurement for impact force is Newtons (N). This is the standard unit for force in the International System of Units (SI).

## 3. What factors affect the calculation of impact force?

The calculation of impact force is affected by several factors, including the mass and velocity of the object, the duration of the impact, and the materials involved in the collision.

## 4. How is impact force used in real-world applications?

Impact force calculations are used in various real-world applications, such as designing safety features for vehicles, determining the safety of sports equipment, and evaluating the potential damage from natural disasters.

## 5. Can you calculate impact force without knowing the velocity?

No, the velocity of the object is a crucial component in calculating impact force. Without knowing the velocity, the impact force cannot be accurately determined.

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