When Sir Isaac Newton first felt an apple bouncing on his head, the theory of roller coaster motion was born
When a rider is on a coaster, Newton’s laws of motion are probably the last thing on their mind, but every physically exciting element of the ride relies entirely on physics
The coaster moves in the same way a marble would roll down an inclined surface
Potential energy is collected by an object as it moves up or away from the Earth
A roller coaster gains potential energy as it is pulled up the hill to its highest point; the train gains more potential energy the further it goes
Lifting the hill gives the coaster “potential” energy
When an object falls back to Earth, it gathers kinetic energy
The transfer of potential energy to kinetic energy occurs when the train leaves the top of the elevator hill and descends the first drop
The greater the potential energy in the train collected during the uphill climb, the more kinetic energy the train will have at the bottom of the descent
Coaster rails control the angle of descent, meaning the steeper the first drop, the greater the kinetic energy
The kinetic energy at the bottom of the drop determines how far the submarine can travel along the track and through inversions, turns and uphills
The calculation between uphill and drop height must be accurate, otherwise the train will not gather enough potential and kinetic energy to complete the circuit
Pad designers then have to consider what happens after the first drop
If the track were perfectly straight and level after the first drop, the kinetic energy would, in theory, allow the train to keep moving forever, because the energy doesn’t disappear
However, in the real world, such forces of air resistance and friction between wheel and track dissipate kinetic energy
The train will stop moving with no kinetic energy
Situation 2: An element of equal height to the first drop
In this situation, when the train accelerates down the first drop and climbs the second element, it rolls back
Although, theoretically, the train has the kinetic energy to climb a hill of the same size as the first drop, some of the kinetic energy would again be lost due to friction and air resistance
The train would only make it about 3/4 of the way up the second hill before rolling back
Situation 3: An element of less height than the first drop
Provided the element after the first drop is low enough to accommodate the weight of the train, this is the perfect situation to allow the coaster to continue to the next element
Several forces are felt when riding on a coaster, and keeping them within safe values is a vital skill for coaster designers
G stands for gravity, and the number in front of it represents how many times the force of gravity is felt at a certain point
If the theme park says the rider will experience, for example, 4G, the rider will briefly experience four times the force of gravity
G Forces create the weather that drivers experience
Ejector Airtime is where the rider feels that they are quickly ejected from the coaster
Floater Airtime is a smoother feel where the rider feels weightless
A positive G-force occurs at the bottom of a drop when the train wants to continue moving in the same direction, but the track forces it in a different direction
Positive G forces usually occur on curves or when the train is pulled uphill after going down a grade
For example, on Oblivion at Alton Towers, when the train pulls out of a vertical drop, the riders are briefly hit with a massive 45G
Positive G is when riders feel heavier than downward pressure, as if they are being pushed down into the seat
Negative G’s are usually experienced when a train starts up a hill at high speed or drops suddenly downhill
Negative G is considered the most fun G Force, but also the most dangerous
Negative forces are measured between 0 and >1 G
Anything less than the standard 1G force is considered weightlessness and is what causes the sensation of floating
Good negative G’s should produce a brief sensation of weightlessness
Lateral G forces occur when a train goes around a corner without a bank or a corner that is not banked enough
This usually happens when riders suddenly push to the side, like in flat hairpin turns on wild mouse pads
Most high-speed coasters contain curved corners, which prevent or reduce lateral Gs and convert them into positive Gs
Lateral G’s push riders to one side
Linear G’s occur when the coaster is launched very quickly in a straight line
The human body can tolerate high levels of linear G forces
The Kingda Ka at Six Flags Great Adventure exhibits high linear Gs as it accelerates from 0 to 128 mph in about 35 seconds
Linear G forces pressurize riders during high-speed launches
Linear G power riders rely on their seat
Human tolerance and safe borders
Positive G from head to toe is indicated by +gz
Negative G from foot to head is denoted -gz
Linear G back to chest is denoted -gx
Linear G back to chest is denoted -gx
The lateral G from left to right is marked -gy
The lateral G from left to right is marked -gy
Positive G-Force tolerance
The human body can usually tolerate about +9gz with the help of a protective suit
Positive G-forces become uncomfortable for the human body at +5gz
At 1gz, humans show no ill effects other than gradual aging as this is the natural level on earth
When under high positive G, blood is forced from the head to the feet, so the riders “go gray”
Negative G-force tolerance
The human body shows alarming symptoms at only -2gz, and on a coaster a level higher than -1gz would be considered dangerous
At -1gz, people show a feeling of pressure in the head
When you are under high negative G, the blood rushes to the head and can cause very serious problems with the organs “flush” and cause bleeding in the brain
Linear G-force tolerance
Lateral G-force tolerance
Humans can tolerate high levels of lateral G if properly restrained; otherwise bodily injury may occur