Chris got asked how fast you would need to be going to complete a loop the loop this is what we got.
Marble loop the loop physics.
First the center of the marble doesn t move from 0 to 2r it moves from r to 2r r so the potential energy due to this is smaller than mg 2r which is what you had in your expression.
First we need to find the minimum speed required at the top of the loop.
What is the minimum height that a mass can be released from rest and still make it around the loop without falling off.
It takes extra energy for the marble to stay on the track so it has to slow down when it goes through the loop.
Abstract this is a really fun project even if you don t like going on roller coasters yourself.
For ease we ll ignore friction.
We are going to find the minimum speed you require to complete the loop we ll do this via an energy argument.
Build a miniature roller coaster and see if you can get marbles to go the distance and upside down.
Loop the loop with a little physics.
When you let go of the marble its potential energy is converted into kinetic energy the energy of motion.
A loop the loop track consists of an incline that leads into a circular loop of radius r.
I solve the loop the loop first year undergraduate and ap physics problems.
First we need to know the minimum speed at the top of the loop for the mass to remain on the track.
You ll build a roller coaster track for marbles using foam pipe insulation and masking tape and see how much of an initial drop is required to get the marble to loop the loop.
Your expression for the velocity looks right.
On the other hand you need to take account of the energy of the sphere rolling which is stated explicitly.