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

[Tozos]

TL;DR

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

 

[phinds]

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.

 

[DaveC426913]

Also, you should seek medical help.

 

[Tozos]

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?

 

[DaveC426913]

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.

 

[Tozos]

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?

 

[pinball1970]

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.
There is a rule about not giving medical advice on pf.
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.

 

[Tozos]

You saw the Dr he said fine so this is a purely academic exercise, ok.
There is a rule about not giving medical advice on pf.
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

 

[pinball1970]

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]

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

Thank you so much for your help! Approximate how many g force would that be?

 

[pinball1970]

Thank you so much for your help! Approximate how many g force would that be?

I am answering your question but I am not a physicist just for your ref.
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

 

[Bystander]

"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?

 

[berkeman]

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

Can you provide a link to where you read that? Thanks.

 

[pinball1970]

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]

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?

 

[pinball1970]

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]

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?

 

[pinball1970]

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

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.

 

[phinds]

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?

 

[Tozos]

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 :)

 

[gleem]

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

 

[DaveC426913]

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.

 

[Tozos]

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?

 

[hutchphd]

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]

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.

 

[hutchphd]

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

 

[Tozos]

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.

 

[DaveC426913]

How can a 5g hit cause a concussion?

Bad luck.

 

[berkeman]

How can a 5g hit cause a concussion?

Bad luck.

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?"