# How many G forces did I experience during my head hit?

• Tozos
In summary, the force of the hit was indeterminate. However, based on your height and weight, it is safe to say that you experienced some G force.
Tozos
TL;DR Summary
How many G forces did I experience during my hit?
Hi,

I just hit my head on the top of my car door as I was leaving my car; the hit hurt my head a lot and I am worried that I received a concussion. However, I read that most concussions require more than 65 Gs of force to be classified a concussion which is why I am wondering if someone here can help determine the force of my hit as I left my car.

My height is 5"9 and my weight is 180.

Thank you

Tozos said:
Summary: How many G forces did I experience during my hit?

Hi,

I just hit my head on the top of my car door as I was leaving my car; the hit hurt my head a lot and I am worried that I received a concussion. However, I read that most concussions require more than 65 Gs of force to be classified a concussion which is why I am wondering if someone here can help determine the force of my hit as I left my car.

My height is 5"9 and my weight is 180.

Thank you
Based on what you said, we can only conclude that you experience some G force. How much is utterly indeterminate with just the information you have given.

russ_watters
Also, you should seek medical help.

phinds said:
Based on what you said, we can only conclude that you experience some G force. How much is utterly indeterminate with just the information you have given.

I sought medical help and they said I was fine - I just want to understand better if there's an approximation of the force received by the blow. Is there any information I can (at least try to) give you to help find a range of force that was delivered?

Tozos said:
I sought medical help and they said I was fine - I just want to understand better if there's an approximation of the force received by the blow. Is there any information I can (at least try to) give you to help find a range of force that was delivered?
Not unless you can tell us the distance between your initial position and the door in centimetres, as well as the angle of your trajectory, and the acceleration you experienced.

If you wanted to set an upper limit, you could put in some numbers and see what kind of G-force would occur in an ideal free fall situation.

DaveC426913 said:
Not unless you can tell us the distance between your initial position and the door in centimetres, as well as the angle of your trajectory, and the acceleration you experienced.
Thank you for the reply - initial position between impact and stationary was 55 centimeters.
The angle is hard to say but I hit the very top of my head, and the acceleration was 1 meter per second.

Does this help provide some type of approximation?

Tozos said:
I sought medical help and they said I was fine - I just want to understand better if there's an approximation of the force received by the blow. Is there any information I can (at least try to) give you to help find a range of force that was delivered?
You saw the Dr he said fine so this is a purely academic exercise, ok.
If you can estimate how quickly you accelerate out of your seat you can get a rough idea of the force.
1 to 2 m/s?
Depends how fast you stand up.
A lot of 'depends' in this.

pinball1970 said:
You saw the Dr he said fine so this is a purely academic exercise, ok.
If you can estimate how quickly you accelerate out of your seat you can get a rough idea of the force.
1 to 2 m/s?
Depends how fast you stand up.
A lot of 'depends' in this.
Yeah this is purely academic / four my own curiosity - I am not seeking medical advice (doctor said I was fine).
I would say I got up about 2 m / s (I was in a hurry).
Does this help provide information about the hit? Thank you for your time

Tozos said:
Yeah this is purely academic / four my own curiosity - I am not seeking medical advice (doctor said I was fine).
I would say I got up about 2 m / s (I was in a hurry).
Does this help provide information about the hit? Thank you for your time
That should be per second every second, it's early here...
2 seems quick and you are using one leg but ok
That's 360N using F=ma where m is your mass in kg
I'm always using wiki so here is a different one
http://zonalandeducation.com/mstm/physics/mechanics/forces/Newton/mightyFEqMA/mightyFEqMA.html

Tozos said:
Thank you so much for your help! Approximate how many g force would that be?
Gs are related to how fast you are traveling, you can feel it if you corner fast in your car. I do not want to give you a clumsy answer so have a look at this.

https://science.howstuffworks.com/science-vs-myth/everyday-myths/question633.htm

"The knee bone' s connected to the...'s connected to the neck bone's connected to the head bone...," in what way? How healthy/arthritic?

Tozos said:
Summary: How many G forces did I experience during my hit?

I read that most concussions require more than 65 Gs of force to be classified a concussion

Tozos said:
Thank you for the reply - initial position between impact and stationary was 55 centimeters.
The angle is hard to say but I hit the very top of my head, and the acceleration was 1 meter per second.

Does this help provide some type of approximation?
It would not be the full 180 lbs as most of your body is on the floor, legs lower body.
Also I should have converted to kg so about 80kg so a % of 80kg X 1-2m/s/s
This is also not taking the angle into account but for simplicity we can say it's close to 180deg.
So between 80 and 160 X half (body weight involved) max 80N
360N would probably do some serious damage.
80N spread over the inside of your door frame will make you see stars for a second and give you a bump.
You have a bump?

Tozos
pinball1970 said:
It would not be the full 180 lbs as most of your body is on the floor, legs lower body.
Also I should have converted to kg so about 80kg so a % of 80kg X 1-2m/s/s
This is also not taking the angle into account but for simplicity we can say it's close to 180deg.
So between 80 and 160 X half (body weight involved) max 80N
360N would probably do some serious damage.
80N spread over the inside of your door frame will make you see stars for a second and give you a bump.
You have a bump?
Thank you for the response - no bump! This is purely an academic question since the doctor said I was fine.

I did have a slight headache after so I wanted to know the force that my hit resulted in. How much is 80N converted to G-force? If this calculation is not possible, is there a way to calculate the G force impacted on my hit based on the information provided?

Tozos said:
Thank you for the response - no bump! This is purely an academic question since the doctor said I was fine.

I did have a slight headache after so I wanted to know the force that my hit resulted in. How much is 80N converted to G-force? If this calculation is not possible, is there a way to calculate the G force impacted on my hit based on the information provided?
If you were accelerating at 1-2m /s/s you can you hit with max 2g

Tozos
pinball1970 said:
If you were accelerating at 1-2m /s/s you can you hit with max 2g
Thank you so much. Out of curiosity, if I were to be experiencing a free fall and I fall on my head (assuming I’m 84kilos), how far would I have to fall in order to experience 35 gs of force?

It would not be the full 180 lbs as most of your body is on the floor, legs lower body.
Also I should have converted to kg so
Tozos said:
Thank you so much. Out of curiosity, if I were to be experiencing a free fall and I fall on my head (assuming I’m 84kilos), how far would I have to fall in order to experience 35 gs of force?
I'm starting to get interested in why you are framing the question this way.
Landing on your head is not a good idea. This was an accident yes? @berkeman will be able to fill in the gaps. I have a feeling the smart guys are having fun watching me fumble around with this a little.

pinball1970 said:
I have a feeling the smart guys are having fun watching me fumble around with this a little.
I don't know about the smart guys but us dumb guys are beginning to wonder why the OP has this obsession with g forces to his head. @Tozos are you thinking of applying for a job as a crash dummy?

pinball1970
phinds said:
I don't know about the smart guys but us dumb guys are beginning to wonder why the OP has this obsession with g forces to his head. @Tozos are you thinking of applying for a job as a crash dummy?
Haha I just want to make sure that I didn't get a concussion! Even though the doctor said I was fine I want to double check with science / math. Thank you for the help everyone :)

Since non medical personnel should not give diagnoses check on line for symptoms both immediate and delayed.

berkeman
Tozos said:
Haha I just want to make sure that I didn't get a concussion! Even though the doctor said I was fine I want to double check with science / math. Thank you for the help everyone :)
I had been assuming you were simply interested for the sake of doing some physics.

There is no way you can check with science or math. You could take 30g and be fine; you could take 5g and get a concussion.

DaveC426913 said:
I had been assuming you were simply interested for the sake of doing some physics.

There is no way you can check with science or math. You could take 30g and be fine; you could take 5g and get a concussion.
How can a 5g hit cause a concussion?

Let take your 65g limit as the threshold for damage.
Assume you are moving with speed v and the collision decelerates you smoothly over distance x.
Then
max=mv2/2
a=v2/2x​

So for v=1m/s and a=650m/s2 , x would have to be less than a millimeter for damage to result. I think there is enough fluid in the meningeal space to take care of that.
Notice if your head is traveling at 10 m/s you need 100mm of cushion, which is why people are killed in a 30 mph collision unless restrained.

Tozos
hutchphd said:
Let take your 65g limit as the threshold for damage.
Assume you are moving with speed v and the collision decelerates you smoothly over distance x.
Then
max=mv2/2
a=v2/2x​

So for v=1m/s and a=650m/s2 , x would have to be less than a millimeter for damage to result. I think there is enough fluid in the meningeal space to take care of that.
Notice if your head is traveling at 10 m/s you need 100mm of cushion, which is why people are killed in a 30 mph collision unless restrained.
Interesting! I think that finally answers my question. If I understand then, if the concussion threshold were to be 20g, then the formula to determine how much "space" needed to protect your brain would be; X = (v^2) / 2a = 400 / 1.5^2 = 0.005625 meters. Am I close?
Again I want to state that this is purely an academic / thought provoking question - not trying to get any medical advise here.

I don't understand your algebra but for v=1.5m/s the result is correct. Do not try this at home...

Tozos
hutchphd said:
I don't understand your algebra but for v=1.5m/s the result is correct. Do not try this at home...

Thank you very much - not trying anything at home. I am taking this opportunity to learn more about physics which is interesting to me.

hutchphd and phinds
Tozos said:
How can a 5g hit cause a concussion?

pinball1970
Tozos said:
How can a 5g hit cause a concussion?
DaveC426913 said:
Also, repeated blows to the head will cause more serious conscussions with less force. That's why one of the first questions your doctor probably asked you in the concussion exam was, "Have you hit your head at all recently? Have you had any other falls recently?"

## 1. What are G forces and how are they measured?

G forces, also known as gravitational forces, are a measure of the acceleration experienced by an object relative to its mass. They are typically measured in units of "g," with 1 g being equal to the force of gravity on Earth (9.8 meters per second squared).

## 2. How do G forces affect the human body?

G forces can have a significant impact on the human body, depending on the magnitude and duration of the force. They can cause discomfort, loss of consciousness, or even permanent injury or death if experienced at high levels.

## 3. What is the maximum G force a human can withstand?

The maximum G force a human can withstand varies depending on the individual and the direction of the force. Generally, a person can withstand up to 5 g's for a short period of time, but anything above 9 g's is likely to be fatal.

## 4. How can G forces be calculated?

G forces can be calculated using the formula F=ma, where F is the force, m is the mass of the object, and a is the acceleration. This formula can be used to determine the G forces experienced during a head hit by measuring the mass of the head and the acceleration it undergoes during impact.

## 5. What factors can affect the G forces experienced during a head hit?

The G forces experienced during a head hit can be affected by various factors such as the speed and direction of impact, the angle of impact, and the surface or object that the head hits. Additionally, the use of protective gear, such as helmets, can help reduce the G forces experienced during a head hit.

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