I had the following conversation with ChatGPT about my November 2021 motorcycle accident. I have edited its responses to remove some redundancy.
Estimate the distance travelled by a person wearing a leather jacket and cotton jeans, sliding over a chipseal road surface, when their starting velocity was 100 kph.
To estimate the distance travelled by a person wearing a leather jacket and cotton jeans sliding over a chipseal road surface when their starting velocity was 100 kph, we need to make some assumptions and use some physics equations.
Assumptions:
- The person is sliding horizontally with no vertical motion.
- The person is in a stable position and not tumbling or rotating.
- The coefficient of kinetic friction between the leather jacket/cotton jeans and the chipseal road surface is 0.7 (a reasonable estimate for dry asphalt).
Using the equation for the distance traveled during constant acceleration, which is:
d = (v^2 – u^2) / (2a)
where:
- d is the distance traveled
- v is the final velocity (which we assume is 0, since the person eventually stops)
- u is the initial velocity (100 kph, which needs to be converted to m/s)
- a is the acceleration (which we can calculate using the coefficient of friction and the gravitational acceleration)
Converting the initial velocity to m/s:
100 kph = 27.8 m/s
Calculating the acceleration using the coefficient of friction and gravitational acceleration:
a = μg
a = 0.7 * 9.81 m/s^2
a = 6.87 m/s^2
Plugging in the values:
d = (0^2 – 27.8^2) / (2 * 6.87)
d = 223.5 meters
Therefore, the distance traveled by a person wearing a leather jacket and cotton jeans sliding over a chipseal road surface when their starting velocity was 100 kph is approximately 223.5 meters.
If I only slid 80 metres in the above scenario, what is the likely reason?
If the person only slid 80 meters in the above scenario where their starting velocity was 100 kph and assuming the same conditions and assumptions, there are several possible reasons for this:
- The coefficient of kinetic friction between the leather jacket/cotton jeans and the chipseal road surface might be lower than the assumed value of 0.7. This could be due to various factors, such as the road surface being wet or oily, or the clothing materials being worn or damaged.
- The person might have encountered an obstacle or a change in the road surface that caused them to slow down or stop earlier than expected. For example, there could have been a pothole, a bump, or a change in the road gradient that caused the person to lose momentum.
- The person might have tried to slow down or stop themselves by applying some form of friction or resistance, such as using their hands or feet, which would have reduced their sliding distance. This could be a deliberate action, such as attempting to slow down and stop as quickly as possible, or an involuntary reflex, such as putting out a hand to break a fall.
- There might be errors or inaccuracies in the initial assumptions or calculations. For example, the person’s actual mass and surface area in contact with the road surface could be different from the assumed values, or there could be other factors affecting the sliding distance that were not considered in the original analysis.
In any case, it is important to note that the calculation of the sliding distance is based on several assumptions and simplifications, and the actual distance traveled by a person sliding on a road surface can vary significantly depending on the specific conditions and circumstances.
How much force is needed to break a person’s ribs?
The amount of force needed to break a person’s ribs can vary widely depending on various factors, such as the person’s age, sex, health status, and the angle and location of the impact. Generally, ribs are more susceptible to fractures from a direct blow or compression, and the force required to cause a rib fracture can range from as little as 4 to 5 kgf (kilograms of force) to more than 900 kgf.
In general, a force of 300 kgf or more can cause a rib fracture in most individuals, with some sources citing a range of 200 to 350 kgf.
Estimate the force of a 100 kg person impacting a road surface after falling off a motorcycle – the angle of impact vs the direction of travel is approximately 45 degrees in the x axis (in other words, at a 45 degree angle to the direction of travel).
To estimate the force of a 100 kg person impacting a road surface after falling off a motorcycle at a 45-degree angle to the direction of travel, we can use the principles of Newtonian mechanics.
Assuming that the person is traveling at a constant speed before falling off the motorcycle, the force of impact will depend on the person’s velocity and the angle of impact. Let’s assume that the person is traveling at 20 m/s (approximately 72 km/h) and impacts the road surface at a 45-degree angle to the direction of travel.
We can break down the force of impact into two components: one perpendicular to the road surface (normal force) and one parallel to the road surface (tangential force). The normal force is equal to the person’s weight, which is 100 kg multiplied by the acceleration due to gravity, which is approximately 9.81 m/s^2, or 981 N. The tangential force is equal to the person’s momentum in the direction of travel at the moment of impact, which is 100 kg multiplied by 20 m/s multiplied by the sine of 45 degrees (since the angle of impact is 45 degrees to the direction of travel), or approximately 1414 N.
The total force of impact is equal to the vector sum of these two components, which we can calculate using the Pythagorean theorem:
force = sqrt(normal force^2 + tangential force^2)
force = sqrt((981 N)^2 + (1414 N)^2)
force = sqrt(1974061 N^2)
force = 1405 N (approximately)
Therefore, the force of a 100 kg person impacting a road surface after falling off a motorcycle at a 45-degree angle to the direction of travel and traveling at 20 m/s is estimated to be approximately 1405 N.
Recalculate the above for an initial velocity of 100 kph.
Sure! Let’s recalculate the force of impact for an initial velocity of 100 km/h, which is equivalent to approximately 27.8 m/s.
Assuming that the person impacts the road surface at the same 45-degree angle to the direction of travel, we can use the same principles of Newtonian mechanics to calculate the force of impact.
The normal force, which is equal to the person’s weight, is still 100 kg multiplied by the acceleration due to gravity, or approximately 981 N.
The tangential force, which is equal to the person’s momentum in the direction of travel at the moment of impact, is now 100 kg multiplied by 27.8 m/s multiplied by the sine of 45 degrees, or approximately 1961 N.
Using the Pythagorean theorem to find the total force of impact:
force = sqrt(normal force^2 + tangential force^2)
force = sqrt((981 N)^2 + (1961 N)^2)
force = sqrt(5762042 N^2)
force = 2400 N (approximately)
Therefore, the force of a 100 kg person impacting a road surface after falling off a motorcycle at a 45-degree angle to the direction of travel and traveling at 100 km/h is estimated to be approximately 2400 N.
Is that sufficient force to break bone?
Yes, a force of 2400 N is sufficient to break bones, including ribs, depending on the location and angle of impact, the age and health of the person, and other factors.
Bone fractures can occur due to a variety of forces, and the amount of force required to cause a fracture can vary widely depending on the bone in question and the specific conditions of the impact. However, a force of 2400 N can certainly cause bone fractures, particularly if the impact is focused on a small area of the body, such as the ribs or the pelvis.
How much force mitigation does D3O armour provide?
D3O is a brand of smart material that is used in a variety of impact protection applications, including motorcycle armor, sports protective gear, and phone cases. The unique properties of D3O are its ability to be flexible and pliable in normal use, but to instantly harden and absorb impact energy when subjected to sudden shocks or impacts.
According to the D3O website, the material is capable of reducing the amount of force transmitted by up to 50% compared to traditional foam-based materials. However, the specific level of protection provided by D3O armor can vary depending on the specific design and application of the armor, as well as the nature and severity of the impact.
How much force reduction does “traditional foam-based materials” used in motorcycle armour typically provide?
According to some studies and industry sources, foam-based armor can reduce the amount of force transmitted by up to 30% compared to unprotected impact areas. However, the specific level of protection provided by foam-based armor can vary widely depending on the specific type and quality of foam used, as well as the nature and severity of the impact.
If foam-based materials reduce force transmission by up to 30%, and D3O provides 50% more force production than that, what is the total amount of force reduction for a 2400 N impact.
If foam-based materials reduce force transmission by up to 30%, and D3O provides 50% more force reduction than that, the total amount of force reduction for a 2400 N impact with D3O armor would be:
- Foam-based materials reduce force transmission by up to 30%, which means that they would reduce a 2400 N impact force by up to 30%, or by 720 N.
- D3O provides 50% more force reduction than foam-based materials, which means that it would reduce a 2400 N impact force by an additional 50% of the 30% reduced by foam-based materials, or by 360 N.
- Therefore, the total amount of force reduction for a 2400 N impact with D3O armor would be 720 N (from foam-based materials) + 360 N (from D3O) = 1080 N, or approximately 45% of the original impact force.
Does this reduce the force of a 2400 N impact low enough to reduce the risk of bone fracture?
A force reduction of 1080 N could certainly help to reduce the risk of bone fracture compared to an impact with the full 2400 N force. Additionally, protective gear like D3O armor can help to distribute impact forces more evenly across the body, reducing the risk of localized injuries to specific bones or body parts.
Assume the 2400 N impact took place on the shoulder (with D3O armour) and the hip (no armour). What are the likely outcomes from this impact?
Bsed on the scenario you described (shoulder impact with D3O armor, hip impact without armor), we can make some general predictions about the likely outcomes:
- Shoulder impact with D3O armor: If the impact was absorbed by D3O armor on the shoulder, it is likely that the force of the impact would be significantly reduced, potentially reducing the risk of shoulder injury. However, it’s still possible that the wearer could experience some pain or discomfort in the shoulder area, particularly if the impact was at an angle or if the force was transmitted to other parts of the body. If the impact was severe enough, there is still a risk of shoulder injury, such as a fracture or dislocation.
- Hip impact without armor: If the impact was not protected by any armor on the hip, the force of the impact would likely be transmitted directly to the bones and tissues in the hip area. This could result in a range of injuries, from bruises and contusions to more severe injuries such as fractures, dislocations, or soft tissue damage.
I survived the above scenario (impact against the road at 100 kph plus an 80 metre slide down the road) with only minor injuries after a motorcycle crash. Is that a statistically likely outcome of this type of crash?
It’s difficult to determine the statistical likelihood of any specific outcome in a motorcycle crash, as the severity of injuries can vary widely depending on many factors, including the specific location and direction of the impact, the age and physical condition of the rider, the presence of protective gear, and many other factors.
That being said, surviving a motorcycle crash with only minor injuries after impact at 100 kph and an 80-meter slide down the road is certainly a positive outcome, and it suggests that the rider was likely wearing appropriate protective gear and following safe riding practices.
