How the Classic Loop the loop works

In summary, the concept that is being discussed here is the conservation of energy in a loop-the-loop problem. It is important to note that even though there is no force explicitly keeping the ball at the top of the loop, the combination of tangential velocity and centripetal acceleration from the normal force and gravity allows the ball to follow the track instead of falling straight down. This can be compared to a projectile with the same velocity, which also moves in a curved path due to its horizontal velocity. However, the ball on the track will accelerate downwards faster due to the additional acceleration from the track's normal force. The ball will only stay on the track if the angle of the tangent to the track is more downwards-pointing than the ball's
  • #1
PhysicsInNJ
44
1
Through some of the conservation of energy problems we've been working recently with the loop the loop (ball rolls down ramp and around a circular track.) there is one concept that is irritating me. This is not a homework problem but a mash up of the driving concepts from a few different problems.

At the top, what makes the ball stay up there. The normal force and gravity both point downward. There is no force keeping it up. Or is it that the combination of tangential velocity caused by centripetal acceleration along with the downward forces acts to make the motion follow the loop.

Also, to clarify, the centripetal force in this case would be Fn and Fg right?
 
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  • #2
PhysicsInNJ said:
At the top, what makes the ball stay up there. The normal force and gravity both point downward. There is no force keeping it up.
It's not being kept up. It's being accelerated downwards by both gravity and the normal force. But it moves down in a curve that follows the track rather than straight down, because it has horizontal velocity.

A useful comparison is with a projectile like a flung pebble that has the same velocity as the ball. It too is being accelerated downwards, but doesn't fall straight down because of its horizontal velocity component. The ball on the track will accelerate downwards faster than a flung pebble right next to it (but slightly away from the track), with the same velocity, because the ball has the additional downwards acceleration from the track's normal force.

As I'm sure you know, if the ball is going too slowly, it will fall away from the track when it nears the top.

The basic rule is that the ball will stay on the track as long as the angle of the tangent to the track is more downwards-pointing than the ball's velocity vector.
 
  • #3
So basically its like a projectile that happens to be following the path of the loop
 

Related to How the Classic Loop the loop works

1. How does the classic loop the loop work?

The classic loop the loop is a gravity-powered roller coaster element that works by converting potential energy into kinetic energy. As the coaster train reaches the top of the loop, it has a high amount of potential energy due to its elevated position. As it begins to descend, the potential energy is converted into kinetic energy, giving the train enough speed and momentum to complete the loop and continue along the track.

2. What is the shape of the classic loop the loop?

The classic loop the loop is a circular loop with a constant radius. This shape allows the train to maintain a consistent speed and direction throughout the loop, ensuring a smooth and safe ride for passengers.

3. How is the classic loop the loop designed to prevent the train from falling off the track?

The classic loop the loop is designed with a larger radius at the top and bottom of the loop and a smaller radius at the apex. This change in radius creates a centripetal force that keeps the train on the track and prevents it from falling off. Additionally, the track is also designed with extra supports and reinforcement to withstand the force and weight of the train.

4. What factors affect the success of a classic loop the loop?

The success of a classic loop the loop depends on several factors, such as the speed and weight of the train, the shape and size of the loop, and the force of gravity. If the train does not have enough speed or momentum, it may not have enough energy to complete the loop. The shape and size of the loop also play a crucial role in maintaining the train's speed and direction, while gravity provides the necessary force to keep the train on the track.

5. Is the classic loop the loop safe for riders?

When designed and executed properly, the classic loop the loop is a safe element for riders. Engineers take into account factors such as speed, weight, and track design to ensure that the train can successfully complete the loop without any safety concerns. Regular inspections and maintenance also help keep the loop safe for riders. However, it is essential to follow safety instructions and height restrictions to avoid any potential risks.

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