Car Collisions
Physics of Car Crashes INTERNAL - Notes
INJURIES TO A HUMAN:
During a car crash, there are three different collisions that occur. The first one is the collision of the car and the opposing object, the second is the human inside the car and the car itself. The final collision is the ones that occur within the human body itself.
BRAIN:
The human brain is protected by the cranial cavity or the skull. The brain is suspended in a substance called the cerebral spinal fluid, which is denser than the skull itself. In a collision, the brain and cerebral spinal fluid begin both begin to move, at different rates than each other. The cerebral spinal fluid will then displace the brain in the opposite direction than the original impact, as the fluid moves …show more content…
to the front of the skull. This can cause the brain to hit the back of the skull and then rebound and hit the front of the skull, causing serious brain injuries and damaging the neurons.
HEART:
Car collisions can also cause tissue within the body to rip and tear. One example is in the heart. In the heart, the ascending aorta and the arch are mobile while the descending aorta is fixed. Therefore, during an actual collision, the descending aorta will decelerate along with the body, while the ascending aorta and the arch will continue moving forward. This will then cause a tear where the two parts of the aorta meet. https://www.youtube.com/watch?v=hi2FEyV2Z2E PHYSICS IDEAS - WHAT CAUSES AN OBJECT TO STOP?
NEWTONS 3 LAWS OF MOTION IN CAR CRASHES:
Newtons first law of motion is the law of inertia. This law states that an object will remain at rest or in uniform motion in a straight line until an external force is acted upon it. This law affects the occupants in a vehicle and is can be seen. When you drive a car at 50km per hour, you are not moving, relative to the car itself. However, you are moving at the same speed of the car. So, when the car smashes into a brick wall, the front of the car begins to crumple up, causing the car to decelerate. Because you are in uniform motion, you continue to move at the same speed/velocity until you hit the steering wheel or the windshield. This is because you are a body in motion travelling at 50kmph and you remain travelling at that speed/velocity in the same direction until you are acted on by an outside force. In this case, it is the force of the steering wheel which overcomes your original inertia. Therefore, it’s important to have your seatbelt on driving as you slow down along with the compartment.
Newtons second law is often expressed in the equation F=ma. Where ‘F’ is the force needed to move an object with the mass, ‘m’, and the acceleration ‘a’. If you were driving a Lamborghini Veneno Roadster on a straight road with a mass of 1490 kgs, as seen on the Lamborghini website (https://www.lamborghini.com/en-en/models/one-off/veneno-roadster), and accelerated to 28ms-1 in 2.8 seconds, you acceleration would be 10ms-2. https://www.zeroto60times.com/vehicle-make/lamborghini-0-60-mph-times/. Therefore, the overall force it would take to stop a Lamborghini Veneno Roadster at this rate of acceleration, immediately, would be 1490 x 10 = 14,900N. If we compare this with a car which is more common, let’s take for example the 2017 Toyota Corolla, with a gross mass of 1735kg (https://www.auto123.com/en/new-cars/technical-specs/toyota/corolla/2017/base/ce/#dimensions) . If you were driving the Toyota corolla on a straight road and accelerated to 28ms-1 in 8.5 seconds, your acceleration would be 3.3ms-1. Because F=ma, the force required to stop the car immediately would be 5725.5 N. (https://www.caranddriver.com/reviews/2017-toyota-corolla-automatic-test-review) . The Lamborghini car required a much larger force to be stopped immediately, nearly 3x as much as the Toyota Corolla. Even though the mass of the Toyota was larger, the Lamborghini could accelerate more rapidly, therefore causing the net force of the Lamborghini to be larger and therefore causing the forces of friction/drag and thrust to be more unbalanced.
Newtons third law states that every action has an equal and opposite reaction. If you were driving the same Lamborghini car as above, at the same velocity, the force required to stop you and the car immediately would be 14,900N. If you crashed into a solid brick wall at that speed, you would be applying 14,900 N of force to the brick wall and because of Newtons 3rd law, the wall would also be applying the same amount of force on the car itself.
MOMENTUM AND IMPULSE:
Momentum is often defined as the quantity of motion and is often expressed in the formula p=mv, where p is momentum, m is mass and v is velocity.
An impulse is something that changes an objects momentum, and is the product of force and the time which that force acts. Impulse is expressed in the equation Impulse=Ft, where F is the force and t is the time on which that force is applied. Impulse is essentially the change in momentum of an object.
If we a car with a mass of 1500kgs was driving at a velocity of 20ms-1, its momentum would be 30,000kgms-1. If we assume that this vehicle crashed into a solid concrete wall, with the time taken being 0.05s, we can calculate the force that the car exerts on the wall and the force the wall exerts on the car. All we need to do is rearrange the equation Impulse=Ft to F=Impulse/t. Because the impulse is the change in momentum (final-initial), the impulse would be 30,000kgms-1.
30,000/0.05 = 600,000N.
The force that is applied to the wall and the wall applies to the car is a colossal 600,000N. What this would look like to a human is simple. The stronger bone in the body, the femur would, on average, take about 4000N to break, meaning that the force of this crash could break the human femur 150 times. Because there are 206 bones in the human body, the force of this crash could break about 73% of the total bones in the human body, most likely killing …show more content…
them.
Newton theorised that momentum in a collision is conserved, this eventually became known as the Law of Conservation of Momentum. Momentum has a directional property, so we call it a vector quantity. This means that if two identical vehicles travelling at 60kmph collided head on, the momentum cancel each other out. The passengers of both cars would experience equal amount of deceleration and therefore an equal amount of force. However, if two cars of different masses collided head-on, the heavier car would push the lighter car backward and therefore the lighter car would experience a much higher acceleration/deceleration change than the lighter car. Because of this, they would then experience much higher forces.
This idea is one that is applied in modern societies in many forms, the most prominent being the crumple zones in an automobile.
WHY SPEED IS AN IMPORTANT FACTOR?
Speed/Velocity is one of the most critical points in a car crash and is related to the amount of energy that is present is a car collision. We can demonstrate this using the formula Ek = 1/2mv2. This formula says that the amount of kinetic energy is equal to the mass multiplied by the velocity squared. Therefore, the amount of kinetic energy an object has, depends on the objects mass and it velocity (squared). The greater the mass, the kinetic energy, the greater the velocity, the greater the kinetic energy. If we do the math we can see why the speed is such a critical factor in the energy involved in a car collision.
If we use the Toyota Corolla example, it has a mass of 1735kg and we assume that it was going at 21ms-1 the total kinetic energy would be:
Ek=1/2 x 1735 x 212
Ek=876.5 x 212 => 876.5 x 441
Ek=366,536.5 J
We will now use the same Toyota Corolla example, keeping the mass constant, but doubling the velocity of the car.
Ek=1/2 x 1735 x 422
Ek=876.5 x 422 =>876.5 x 1764
Ek=1,546,146 J
1,546,146/366536.5 = 4.22
As we can see through these equations, when we double the speed of an object, we quadruple the amount of energy involved in a car collision. This is why speed is such a crucial factor in the outcome of a car collision, as even increasing the speed a meagre 10kmph, can significantly impact the outcome of a car collision an end a life of a loved one.
FEATURES IN CARS TO HELP INCREASE STOPPING DISTANCE AND HELP PASSENGERS:
Cars and other automobiles are engineered in a certain way and include certain features to help the occupants of the vehicle’s survival being the top priority of the car. Engineers design automobiles so that the occupants/passengers’ survival is the top priority. One of these features in cars is the crumple zone.
Early automobile designs saw extremely rigid car frames that were very resistant in various accidents. Because of this flawed theory, the cars would end up surviving the collision, however, the occupants of the car would not survive the fatal injuries.
(
https://www.autoevolution.com/news/how-crumple-zones-work-7112.html). This relates back to the equations, F=ma; and Impulse=Ft. Because the rigid car frames were very resistant, the time of the impact was extremely small, and therefore causing the occupants of the car to experience greater acceleration/deceleration and increased forces, which could be fatal to the human body. In other words, as the time of the impact increases, the force exerted and experienced decreases.
It wasn’t until 1953 until the first crumple zones were implemented on automobiles. The company responsible for the innovation was Mercedes-Benz. The Crumple Zone theory explains why Crumple Zones are necessary for vehicles, especially in the modern age. Crumple Zones are placed at the front and rear end of cars and most cars have around 50cm to dissipate the energy. Over half of the crumpling work is done by a pair of steel rails which connect the front bumper to the body. During a collision, these rails bend and deform to absorb the energy and increase the time of the impact and therefore decreasing the time of the impact. This means that less energy and force is required to stop the car and the passengers. Because of the crumple zones, the survival rate of car crashes has increased significantly. (https://www.youtube.com/watch?v=v9ML4GA47Rg).
One feature that is present in all cars is an airbag. An airbag is a feature that can significantly increase the survival rate of a person in a car crash. This is how an airbag works:
INJURIES TO A HUMAN:
During a car crash, there are three different collisions that occur. The first one is the collision of the car and the opposing object, the second is the human inside the car and the car itself. The final collision is the ones that occur within the human body itself.
BRAIN:
The human brain is protected by the cranial cavity or the skull. The brain is suspended in a substance called the cerebral spinal fluid, which is denser than the skull itself. In a collision, the brain and cerebral spinal fluid begin both begin to move, at different rates than each other. The cerebral spinal fluid will then displace the brain in the opposite direction than the original impact, as the fluid moves …show more content…
to the front of the skull. This can cause the brain to hit the back of the skull and then rebound and hit the front of the skull, causing serious brain injuries and damaging the neurons.
HEART:
Car collisions can also cause tissue within the body to rip and tear. One example is in the heart. In the heart, the ascending aorta and the arch are mobile while the descending aorta is fixed. Therefore, during an actual collision, the descending aorta will decelerate along with the body, while the ascending aorta and the arch will continue moving forward. This will then cause a tear where the two parts of the aorta meet. https://www.youtube.com/watch?v=hi2FEyV2Z2E PHYSICS IDEAS - WHAT CAUSES AN OBJECT TO STOP?
NEWTONS 3 LAWS OF MOTION IN CAR CRASHES:
Newtons first law of motion is the law of inertia. This law states that an object will remain at rest or in uniform motion in a straight line until an external force is acted upon it. This law affects the occupants in a vehicle and is can be seen. When you drive a car at 50km per hour, you are not moving, relative to the car itself. However, you are moving at the same speed of the car. So, when the car smashes into a brick wall, the front of the car begins to crumple up, causing the car to decelerate. Because you are in uniform motion, you continue to move at the same speed/velocity until you hit the steering wheel or the windshield. This is because you are a body in motion travelling at 50kmph and you remain travelling at that speed/velocity in the same direction until you are acted on by an outside force. In this case, it is the force of the steering wheel which overcomes your original inertia. Therefore, it’s important to have your seatbelt on driving as you slow down along with the compartment.
Newtons second law is often expressed in the equation F=ma. Where ‘F’ is the force needed to move an object with the mass, ‘m’, and the acceleration ‘a’. If you were driving a Lamborghini Veneno Roadster on a straight road with a mass of 1490 kgs, as seen on the Lamborghini website (https://www.lamborghini.com/en-en/models/one-off/veneno-roadster), and accelerated to 28ms-1 in 2.8 seconds, you acceleration would be 10ms-2. https://www.zeroto60times.com/vehicle-make/lamborghini-0-60-mph-times/. Therefore, the overall force it would take to stop a Lamborghini Veneno Roadster at this rate of acceleration, immediately, would be 1490 x 10 = 14,900N. If we compare this with a car which is more common, let’s take for example the 2017 Toyota Corolla, with a gross mass of 1735kg (https://www.auto123.com/en/new-cars/technical-specs/toyota/corolla/2017/base/ce/#dimensions) . If you were driving the Toyota corolla on a straight road and accelerated to 28ms-1 in 8.5 seconds, your acceleration would be 3.3ms-1. Because F=ma, the force required to stop the car immediately would be 5725.5 N. (https://www.caranddriver.com/reviews/2017-toyota-corolla-automatic-test-review) . The Lamborghini car required a much larger force to be stopped immediately, nearly 3x as much as the Toyota Corolla. Even though the mass of the Toyota was larger, the Lamborghini could accelerate more rapidly, therefore causing the net force of the Lamborghini to be larger and therefore causing the forces of friction/drag and thrust to be more unbalanced.
Newtons third law states that every action has an equal and opposite reaction. If you were driving the same Lamborghini car as above, at the same velocity, the force required to stop you and the car immediately would be 14,900N. If you crashed into a solid brick wall at that speed, you would be applying 14,900 N of force to the brick wall and because of Newtons 3rd law, the wall would also be applying the same amount of force on the car itself.
MOMENTUM AND IMPULSE:
Momentum is often defined as the quantity of motion and is often expressed in the formula p=mv, where p is momentum, m is mass and v is velocity.
An impulse is something that changes an objects momentum, and is the product of force and the time which that force acts. Impulse is expressed in the equation Impulse=Ft, where F is the force and t is the time on which that force is applied. Impulse is essentially the change in momentum of an object.
If we a car with a mass of 1500kgs was driving at a velocity of 20ms-1, its momentum would be 30,000kgms-1. If we assume that this vehicle crashed into a solid concrete wall, with the time taken being 0.05s, we can calculate the force that the car exerts on the wall and the force the wall exerts on the car. All we need to do is rearrange the equation Impulse=Ft to F=Impulse/t. Because the impulse is the change in momentum (final-initial), the impulse would be 30,000kgms-1.
30,000/0.05 = 600,000N.
The force that is applied to the wall and the wall applies to the car is a colossal 600,000N. What this would look like to a human is simple. The stronger bone in the body, the femur would, on average, take about 4000N to break, meaning that the force of this crash could break the human femur 150 times. Because there are 206 bones in the human body, the force of this crash could break about 73% of the total bones in the human body, most likely killing …show more content…
them.
Newton theorised that momentum in a collision is conserved, this eventually became known as the Law of Conservation of Momentum. Momentum has a directional property, so we call it a vector quantity. This means that if two identical vehicles travelling at 60kmph collided head on, the momentum cancel each other out. The passengers of both cars would experience equal amount of deceleration and therefore an equal amount of force. However, if two cars of different masses collided head-on, the heavier car would push the lighter car backward and therefore the lighter car would experience a much higher acceleration/deceleration change than the lighter car. Because of this, they would then experience much higher forces.
This idea is one that is applied in modern societies in many forms, the most prominent being the crumple zones in an automobile.
WHY SPEED IS AN IMPORTANT FACTOR?
Speed/Velocity is one of the most critical points in a car crash and is related to the amount of energy that is present is a car collision. We can demonstrate this using the formula Ek = 1/2mv2. This formula says that the amount of kinetic energy is equal to the mass multiplied by the velocity squared. Therefore, the amount of kinetic energy an object has, depends on the objects mass and it velocity (squared). The greater the mass, the kinetic energy, the greater the velocity, the greater the kinetic energy. If we do the math we can see why the speed is such a critical factor in the energy involved in a car collision.
If we use the Toyota Corolla example, it has a mass of 1735kg and we assume that it was going at 21ms-1 the total kinetic energy would be:
Ek=1/2 x 1735 x 212
Ek=876.5 x 212 => 876.5 x 441
Ek=366,536.5 J
We will now use the same Toyota Corolla example, keeping the mass constant, but doubling the velocity of the car.
Ek=1/2 x 1735 x 422
Ek=876.5 x 422 =>876.5 x 1764
Ek=1,546,146 J
1,546,146/366536.5 = 4.22
As we can see through these equations, when we double the speed of an object, we quadruple the amount of energy involved in a car collision. This is why speed is such a crucial factor in the outcome of a car collision, as even increasing the speed a meagre 10kmph, can significantly impact the outcome of a car collision an end a life of a loved one.
FEATURES IN CARS TO HELP INCREASE STOPPING DISTANCE AND HELP PASSENGERS:
Cars and other automobiles are engineered in a certain way and include certain features to help the occupants of the vehicle’s survival being the top priority of the car. Engineers design automobiles so that the occupants/passengers’ survival is the top priority. One of these features in cars is the crumple zone.
Early automobile designs saw extremely rigid car frames that were very resistant in various accidents. Because of this flawed theory, the cars would end up surviving the collision, however, the occupants of the car would not survive the fatal injuries.
(
https://www.autoevolution.com/news/how-crumple-zones-work-7112.html). This relates back to the equations, F=ma; and Impulse=Ft. Because the rigid car frames were very resistant, the time of the impact was extremely small, and therefore causing the occupants of the car to experience greater acceleration/deceleration and increased forces, which could be fatal to the human body. In other words, as the time of the impact increases, the force exerted and experienced decreases.
It wasn’t until 1953 until the first crumple zones were implemented on automobiles. The company responsible for the innovation was Mercedes-Benz. The Crumple Zone theory explains why Crumple Zones are necessary for vehicles, especially in the modern age. Crumple Zones are placed at the front and rear end of cars and most cars have around 50cm to dissipate the energy. Over half of the crumpling work is done by a pair of steel rails which connect the front bumper to the body. During a collision, these rails bend and deform to absorb the energy and increase the time of the impact and therefore decreasing the time of the impact. This means that less energy and force is required to stop the car and the passengers. Because of the crumple zones, the survival rate of car crashes has increased significantly. (https://www.youtube.com/watch?v=v9ML4GA47Rg).
One feature that is present in all cars is an airbag. An airbag is a feature that can significantly increase the survival rate of a person in a car crash. This is how an airbag works: