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'G' – forces – Greater the centripetal acceleration, greater the 'g' forces which represent the gravitational pull on the riders. 1G is the usual force of gravity felt on Earth. When you feel weightless you experience 0G.
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Physics Project – The working of a roller coaster
Research Question 2 – List the factors that would affect safety.
Ans. The factors affecting safety are –
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Speed of the coaster : The higher the speed of the roller coaster the more the inertial velocity. The safety harness needs to be present or else your body's inertia would resist change in direction.
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The size and shape of components : Any one component needs to be lower than the previous. The hills are preferably sloped without steep angles and the loop is preferably clothoid.
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The g – forces felt by riders : Both normal and lateral (sideways). If the downward forces experienced by riders’ are too strong, the ride can be uncomfortable and at times even fatal.
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Centripetal acceleration during the loop : If the acceleration is too high during the loop riders' will feel 'sucked' towards the centre at the top at times resulting in fatal neck injuries.
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Riders need to be healthy : Riders' with brain problems, heart problems, high blood pressure should not ride on the coasters. One has to also meet certain height and weight restrictions.
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Physics Project – The working of a roller coaster
Research Question 3 – Why are the loops clothoid and not circular?
Ans. The reason for loops being clothoid and not circular is –
A larger radius means a lower centripetal acceleration. A clothoid shape is like a teardrop. If the loop is circular the centripetal acceleration is constant throughout as the radius is constant.
However, a teardrop shape has a sharper turn at the top which makes the radius smaller. This ensures that the centripetal acceleration is higher at the top.
The coaster can be then sent at a slower speed (fast speeds can be uncomfortable) as the centripetal acceleration at the top is enough to ensure that the coaster completes the loop.
A large radius at the bottom reduces the centripetal acceleration which in turn diminishes the magnitude of he 'g' – forces acting on the riders which make the ride less uncomfortable.
Furthermore, the centripetal forces felt in a circle are so strong at the top (radius is more) that riders' necks can get snapped. Therefore, the loop is clothoid and not a circle.
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Physics Project – The working of a roller coaster
Research Question 4 – What is the purpose of banking of tracks?
Ans. Tracks are banked to serve the following purpose –
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The turns in a roller coaster are banked so that a rider feels as though he is being pushed into his seat rather than being thrown off the carriage due to inertia.
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The tracks are tilted slightly towards the inside of the turn being banked. This allows some of the lateral 'g' – forces (which can be uncomfortable) to be converted into normal, positive 'g' – forces.
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The two forces acting on a rider during the loop are – gravity and the centrifugal force. The resultant is (almost always) downwards but at an angle. Banking of tracks allows the line of action of this resultant force to lie inside the base of the coaster (stability).
Note :- In some roller coasters the tracks are banked towards the outside of the turn. This would result in negative 'g' – forces which makes a rider feel as though he is being pulled upwards!
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Physics Project – The working of a roller coaster
Research Question 5 – When at the top of the loop a rider will feel partially weightless. Why?
Ans. The reasons for weightlessness are –
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At the top of the loop gravity is pulling you downwards and the centrifugal (upward) force is also present. The resultant force is near zero and this is why you feel almost completely weightless.
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When a rider is at the top of the loop he applies a force on the floor of the coaster which can be termed as the riders' 'apparent' weight. The apparent weight acts upwards and adds to the centrifugal force.
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Our body is made up of different organs suspended in a fluid, blood. When we accelerate normally our body parts push each other. However, in a roller coaster as there is hardly any net force acting on the rider so the organs don't push each other as much as they do normally and thus they feel weightless (ex :- Stomach).
Note :- At times the centrifugal (acceleration) forces are so high that the rider feels negative 'g' – forces and feels as though he is being pulled upwards (net force is upwards).
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