# Car crashes, I try to analyze it.

• Ziyonex
In summary, the driver of a car that crashed off a dirt ramp was initially going at a speed of 41 mph, but because of the steep angle of the ramp, the car only traveled a maximum of 18.4 m before stopping. If the angle of the ramp is not 30 degrees, then the car would have travelled a much greater distance and possibly resulted in more damage.
Ziyonex
I feel very stupid right now, but I must figure this out. A friend of mine was in a car wreck; steered off the side of the road and hit a natural dirt ramp. I decided I would try to figure out how long he was in the air for, and how fast he was going initially, but it seems I am just not smart enough, and I'm very frustrated that I can't figure out a simple kinematics problem.

He hit the jump in his car at an unknown velocity. I measured top of the dirt ramp to be about 1.5m from the ground. The car landed about 30m from the edge of the dirt ramp. I measured the angle of the ramp to be about 30 degrees.

I know I have enough information here to calculate all variables in this situation, which is what kills me. If someone could take a few seconds to explain to me how I should go about this, that would be great. I tried two-dimensional kinematics and conservation of energy to try to solve this, but I can't get it.

Driver sustained a minor concussion. Airbag should have deployed, but did not. The enormous Ford Excursion Diesel was totaled.

The 1.5 m tall ramp makes the solution a little more difficult.

However, you can neglect this an get a result that is accurate to within about 7% by using the "level target" standard kinematic solution:

R = vo^2 * sin (2 * angle) / g

x(t) = (vo cos (angle) ) t

where,

R = range = total distance traveled (given)
x(t) = distance traveled as a function of time
vo = initial velocity (solve for)
angle is given.

Try this. If you are interested in including the 1.5m ramp, let me know.

The first formula you gave me yielded an initial velocity of 18.4 m/s or about 41 mph. The speed limit on the road was 60 mph, so that seems a little slow, however there were a few skid marks leading up to the dirt ramp, which could account for the reduced velocity.

How did you derive the first formula you gave me?

Ziyonex said:
The first formula you gave me yielded an initial velocity of 18.4 m/s or about 41 mph. The speed limit on the road was 60 mph, so that seems a little slow, however there were a few skid marks leading up to the dirt ramp, which could account for the reduced velocity.

How did you derive the first formula you gave me?
The derivation is a little length. See Physics by Tipler under projectile motion.

If the launch velocity seems low to you, double check your 30 deg ramp angle. This is fairly steep.

As much as I hate to piss in anyone's cornflakes, the PF policy is to not deal with real-life legal issues. This has arisen several times in the past, and our advice is always to hire a professional accident analyst. It can't be done on-line.
This isn't intended as a put-down, but rather sound legal advice. Nothing that any of us say can be used in court.

## 1. How common are car crashes?

According to the National Highway Traffic Safety Administration, there were over 6.7 million car crashes reported in the United States in 2018.

## 2. What are the main causes of car crashes?

The most common causes of car crashes include distracted driving, speeding, drunk driving, and reckless driving. Other factors such as weather conditions, road hazards, and vehicle malfunctions can also contribute to car crashes.

## 3. What types of injuries are most common in car crashes?

Whiplash, broken bones, and head injuries are some of the most common injuries sustained in car crashes. These injuries can range from minor bruises and cuts to more severe and life-threatening injuries.

## 4. How do car crashes affect individuals and society?

Car crashes can have a significant impact on both individuals and society. Aside from physical injuries, car crashes can cause emotional trauma, financial burden, and loss of productivity. They also result in billions of dollars in economic costs each year.

## 5. What can be done to prevent car crashes?

There are several measures that can be taken to prevent car crashes, such as following traffic laws, avoiding distractions while driving, wearing seatbelts, and not driving under the influence of drugs or alcohol. Regular vehicle maintenance and safe driving practices can also help reduce the risk of car crashes.

Replies
4
Views
2K
Replies
3
Views
15K
Replies
3
Views
1K
Replies
3
Views
1K
Replies
4
Views
5K
Replies
8
Views
2K
Replies
3
Views
2K
Replies
9
Views
4K
Replies
7
Views
2K
Replies
4
Views
1K