Roller coaster loop the loop

Physics with Professor Matt Anderson

10 Apr 201611:10

EducationalLearning

32 Likes 10 Comments

TLDRThe video script delves into the physics of roller coasters, particularly focusing on the sensation of weightlessness experienced during upside-down loops. It explains the forces at play, including gravity and the normal force exerted by the roller coaster seat, through the use of free body diagrams. The script illustrates how these forces contribute to the feeling of being heavier at the bottom of the loop and lighter at the top. It also explores the concept of designing a roller coaster to achieve a sensation of weightlessness at the top, calculating the necessary speed to achieve this. The video concludes with a discussion on the human body's response to weightlessness, including the common feeling of one's stomach moving up into the throat, and touches on the implications for astronaut training.

Takeaways

🎢 The roller coaster ride is compared to a roller coaster that goes upside down, with the car's track, circular loop, and the sensation of being upside down.
💺 When at the bottom of the loop, the force of gravity is balanced by the car's seat pushing you into it, making you feel heavier at the bottom.
📐 To analyze the rotational motion, a freebody diagram is used to consider the forces acting on the car at the top and bottom of the loop.
🌀 At the top, the normal force is directed towards the center of the loop, while at the bottom, it's directed away from the center due to the car's upside-down position.
📊 Newton's second law is applied to calculate the normal force at the top and bottom of the loop, leading to the conclusion that you feel heavier at the bottom due to the larger normal force.
🚀 To design a roller coaster that makes you feel weightless at the top, the normal force must be zero, which can be achieved by setting the car's speed to a specific value.
🛠️ Engineers use this knowledge to ensure safety and excitement in roller coaster design, aiming for a speed that prevents passengers from falling out of their seats.
🤔 The feeling of weightlessness can cause discomfort, as the body's organs, including the stomach, adjust to the absence of the normal force that normally pushes them back up against gravity.
🎉 Roller coaster designers focus on creating moments of weightlessness to enhance the ride's excitement and fun, while also ensuring safety for passengers.
🚀 The speed at which you feel weightless at the top of the roller coaster is calculated using the normal force and the car's mass, ensuring a balance between safety and thrilling experiences.

Q & A

What is the main topic discussed in the script?
-The script discusses the physics of roller coasters, particularly focusing on the forces acting on a person and the sensation of weightlessness during the ride.
Why do people feel heaviest at the bottom of a roller coaster loop?
-People feel heaviest at the bottom of a roller coaster loop because the normal force from the seat is pushing up on them, which adds to the force of gravity, making them feel heavier.
What is a free body diagram and why is it used in this context?
-A free body diagram is a graphical representation of all the forces acting on an object. It is used in this context to analyze the forces acting on a person at the top and bottom of a roller coaster loop.
What are the two forces acting on a person at the top of a roller coaster loop?
-The two forces acting on a person at the top of a roller coaster loop are gravity (Mg), pulling them downward, and the normal force (N) from the seat, also acting downward since they are upside down.
How is Newton's second law applied to the analysis of forces on a roller coaster?
-Newton's second law (F = ma) is applied by considering the sum of the forces acting radially towards the center of the circular path (mg + N) and equating it to the centripetal force required for circular motion (MV^2/R).
What is the formula to calculate the speed at which a person feels weightless at the top of a roller coaster loop?
-The formula to calculate the speed at which a person feels weightless at the top of a roller coaster loop is V = √(Rg), where V is the speed, R is the radius of the loop, and g is the acceleration due to gravity.
Why is it important for roller coaster designers to know the speed at which riders feel weightless?
-It is important for roller coaster designers to know this speed to ensure rider safety and to create an exciting experience. If the speed is less than the calculated value, riders may start to fall out of their seats.
What is the sensation that riders often describe after experiencing weightlessness on a roller coaster?
-Riders often describe a sensation where their stomach feels like it's in their throat, which is due to the organs shifting position when not being pushed back by the floor.
Why do some people feel sick after experiencing weightlessness on a roller coaster?
-Some people feel sick after experiencing weightlessness because their body is not used to the sensation of organs shifting positions, which can cause discomfort and disorientation.
What is the significance of the normal force in the context of roller coaster physics?
-The normal force is significant because it is the force exerted by the seat of the roller coaster on the rider. It affects the rider's perception of weight and is crucial for maintaining safety and providing the sensation of weightlessness.

Outlines

00:00

🎢 Physics of Roller Coasters and Weight Perception

This paragraph explains the physics behind the sensation of weight on a roller coaster. It starts with a common experience of riding an upside-down roller coaster and asks where one feels heaviest - at the top or bottom of the loop. The answer is the bottom due to the increased normal force from the seat. The explanation then moves to a Free Body Diagram (FBD) analysis at the top and bottom of the loop, identifying the forces of gravity (mg) and the normal force (N). Using Newton's second law, the script derives the equations for the normal force at the top (nt = mv^2/r - mg) and bottom (nb = mv^2/r + mg) of the loop. This leads to the conclusion that riders feel heavier at the bottom due to the greater normal force.

05:01

🌌 Designing a Roller Coaster for Weightlessness

The second paragraph delves into the design considerations for a roller coaster that aims to create a sensation of weightlessness at the top of the loop. To achieve this, the normal force at the top must be zero, which implies that the speed of the roller coaster must be calculated to counteract gravity without relying on the seat's normal force. The formula V = sqrt(rg) is derived, where V is the speed, g is the acceleration due to gravity, and r is the radius of the loop. The importance of this speed is highlighted for safety reasons, as falling below this speed could result in riders falling out of their seats. Additionally, the paragraph touches on the excitement and thrill of experiencing weightlessness, which is a key element in roller coaster design for an exhilarating ride.

10:01

🚀 The Unsettling Feeling of Weightlessness

The final paragraph addresses the peculiar sensation people experience during weightlessness, often described as their stomach feeling like it's in their throat. This is explained by the normal gravitational pull on the body being absent, causing the body's organs to relax and shift position. The stomach, which is typically lower in the abdomen due to gravity, rises, leading to the odd feeling. The discomfort associated with weightlessness is also mentioned as a reason why not everyone can be an astronaut, as the sensation can cause motion sickness and disorientation.

Mindmap

Keywords

💡Roller Coaster

A roller coaster is an amusement ride that consists of a track with steep inclines, drops, and often inversions. In the context of the video, it serves as the central example to explain the physics of rotational motion and forces acting on a body. The script uses the roller coaster to illustrate concepts such as weightlessness and the normal force experienced by riders.

💡Circular Loop

A circular loop in the script refers to the part of the roller coaster track where the train turns upside down, creating a circular path. It is crucial for demonstrating the changes in perceived weight due to centripetal forces acting on the riders, which is a key point in the video's explanation of physics.

💡Freebody Diagram

A freebody diagram is a simplified drawing that represents all the forces acting on an object in a particular situation. In the video, it is used to analyze the forces on a roller coaster rider at the top and bottom of a loop, helping to visualize and understand the physics behind the sensations experienced by the rider.

💡Normal Force

Normal force is the perpendicular force exerted by a surface that supports the weight of an object resting on it. The script explains how this force changes as a rider goes through different parts of the roller coaster, particularly noting the increased normal force at the bottom of the loop, which makes riders feel heavier.

💡Gravity

Gravity is the force of attraction by which the Earth (or another celestial body) causes objects to move toward its center. In the video, gravity is described as always acting downward, influencing the forces experienced by riders on the roller coaster and contributing to the sensation of weight.

💡Centrifugal Force

Although not explicitly mentioned in the script, the concept of centrifugal force is implied when discussing the forces at play during the roller coaster's circular loop. It is the apparent force that pushes an object away from the center of a circular path, which is why riders feel lighter at the top of the loop.

💡Weightlessness

Weightlessness is the sensation of having no weight, which occurs when an object or person is in free fall or when the only force acting on them is gravity. The video explains how riders can feel weightless at the top of the roller coaster loop when the normal force from the seat is zero.

💡Newton's Second Law

Newton's Second Law of Motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The script applies this law to calculate the normal force and the speed required for riders to feel weightless at the top of the roller coaster loop.

💡Radial Direction

In the context of the video, radial direction refers to the direction towards or away from the center of the circular path of the roller coaster loop. The forces acting in the radial direction are crucial for understanding the dynamics of the roller coaster and the sensations felt by the riders.

💡Safety

Safety is a critical consideration in the design of roller coasters, as the video script explains the importance of ensuring that riders do not fall out of their seats, especially at the top of the loop. The speed of the roller coaster and the design of the restraints are discussed in relation to maintaining rider safety.

💡Excitement

Excitement is a key aspect of the roller coaster experience that the script touches upon. It is related to the sensation of weightlessness and the thrill of the ride's ups and downs. Roller coaster designers aim to create a balance of excitement and safety to provide a memorable and enjoyable experience for riders.

💡Stomach in Throat

The phrase 'stomach in throat' is used in the script to describe the sensation of disorientation and discomfort some people feel during weightlessness, as their internal organs shift positions. This is an example of how the physical forces experienced on a roller coaster can have physiological effects on the body.

Highlights

The sensation of weightlessness on a roller coaster is discussed, specifically at the top of an upside-down loop.

A roller coaster's circular loop design and the physical experience of passengers are described.

The concept of feeling heaviest at the bottom of the loop due to the normal force is introduced.

Freebody diagrams are used to analyze the forces acting on a roller coaster at the top and bottom of a loop.

Gravity (Mg) and normal force are identified as the primary forces acting on a passenger at the bottom of the loop.

At the top of the loop, gravity and an inverted normal force are the only forces acting on the passenger.

Newton's second law is applied to calculate the normal force at the top (nT) and bottom (nB) of the loop.

The formula nT = MV^2/R - Mg is derived to represent the normal force at the top of the loop.

The formula nB = MV^2/R + mg is derived to represent the normal force at the bottom of the loop.

It is explained why passengers feel heavier at the bottom of the loop due to a larger normal force.

The concept of designing a roller coaster to achieve a sensation of weightlessness at the top is explored.

The speed required to feel weightless at the top of the loop is calculated using the formula V = sqrt(Rg).

The importance of this speed for safety, to prevent passengers from falling out of their seats, is emphasized.

The role of safety belts and roller coaster design in enhancing the thrilling sensation of weightlessness is discussed.

The physical sensation of one's stomach feeling like it's in one's throat during weightlessness is explained.

The discomfort some people feel during weightlessness and its relation to space travel and astronaut training is mentioned.

Transcripts

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