Frequently asked questions from students (This page is still under development)
What is the brain made of?
The brain is a jelly like soft tissue suspended within the enclosure of the hard skull in a bath of cerebral spinal fluid. The brain is covered by three membrane layers in which the outer-most layer, called the dura-mater, is connected to the inside of the skull at various suture points which serve to suspend the brain within the skull. The brain sits atop the brain stem and the spinal cord extends from there. The spinal cord passes out through a hole in the base of the skull called the foramen magnum. The mass of the human brain is roughly 1.5 kg.
What is the mass of the human head?
The mass of the human head is somewhere between 4.5 kg to 5.0 kg which constitutes about 7 per cent to 8 percent of the whole mass of the human body.
What happens if there is a severe impact to the head?
A blow to the travelling head can cause the head to rapidly decelerate (or quickly stop), while the brain continues in it movement, striking the interior of the skull. The inertia effects of the brain keeps it travelling forward to strike the inside surface of the skull.
The impact of the brain against the skull may cause bruising (contusions) and/or bleeding (haemorrhage) to the brain.
A severe blow to the head can cause the brain to bleed at the site closest to the point of impact. This is called a coup injury.
A severe blow to the head can cause the brain to be injured directly opposite the point of impact on the other side of the brain. This is called a contrecoup injury.
Thus it is important to decelerate the head appropriately.
In all types of impacts, the head is subjected to a combined linear and angular (or rotational) acceleration.
Linear acceleration is considered to produce focal brain injuries while rotational acceleration produces both focal and diffuse brain injuries.
If an impact force is applied to the head, the head rotates about its point of articulation but not around its centre of gravity.
If a helmet is placed on the head then there is an increase in mass to the head and if there is an impact to the head then there will be an increase in the rotational acceleration effects of the head, therefore it is important to keep the increase in mass added to the head to a minimum.
The cone-headliner reduces the overall mass of the helmet. As it is a lighter helmet it will reduce the effects of rotational acceleration of the head during impact.
What is the basic Physics behind cone-head?
For helmets, made of one density hard foam, similar to the foam in bicycle helmets, which are involved in an impact, the head will experience a rapid deceleration. In other words there is a high deceleration of the head and the impact time of interaction is short. Hence the forces are readily translated across the thickness of the foam liner to the skull.
(HARD FOAM IN CONTACT WITH HEAD MEANS RAPID DECELERATION --> SHORT IMPACT TIME --> MAJORITY OF FORCE TRANSLATED TO SKULL --> HENCE HARD FOAM IS NOT VERY EFFECTIVE IN ABSORBING IMPACT FORCE)
For helmets with the cone-head liner (i.e. low density cones embedded within the thickness of the higher density foam) and are involved in an impact, the head will experience a gradual deceleration because of the crushing/compression of the cones. The cones reduce the deceleration of the head and the impact time of interaction is longer or the head stopping time is longer. Hence there is a reduction in the forces translated across the thickness of the new shock absorbing liner to the skull.
The cone-head liner is doing work in absorbing an impact force.
(SOFTER FOAM IN CONTACT WITH HEAD MEANS GRADUAL DECELERATION --> LONGER IMPACT TIME --> LESS FORCE TRANSLATED TO SKULL --> HENCE FOAM ABSORBS MAJORITY OF IMPACT FORCE)
What material is the cone-head liner made of?
The material that the cone-head liner is presently made of is expanded polystyrene foam (EPS).
