Particle in a "roller coaster"

In summary: Unless the path from B to C is falling under gravity (no track), then there is no unique solution for the shape of the track from B to C, as @.Scott has said.
  • #1
Celso
33
1
Homework Statement
How can I find ##h_{2}## in terms of the other variables knowing that the horizontal distance between B and C is 10m? (the particle is initially at rest)
Relevant Equations
##E_{i} = E_{f}##
241905

I first found ##v_{B}## by ##E_{p,A,B} = mgh_{1} = E_{c, B} = \frac{1}{2}mv_{B}^2 \therefore v_{B} = \sqrt{2gh_{1}} ##
After this I made several failed attempts basically trying to find its final velocity so I could use conservation of energy. Spliting the velocity into its components never worked because the force in these components varies with the angle as it falls.
 
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  • #2
Are we told anything else?
For example, is that curve supposed to be a cubic curve?

In the segment from B to C, is the particle supported by the track - or is it following a parabolic path?
 
  • #3
That's all, as far as I know. This is actually an
.Scott said:
Are we told anything else?
For example, is that curve supposed to be a cubic curve?

In the segment from B to C, is the particle supported by the track - or is it following a parabolic path?
That's all, the problem's statement is simply "the following picture represents the configuration of a falling objetc". It's actually a problem I tried to solve for another person but I couldn't figure out after an hour
 
  • #4
Celso said:
That's all, as far as I know. This is actually an

That's all, the problem's statement is simply "the following picture represents the configuration of a falling objetc". It's actually a problem I tried to solve for another person but I couldn't figure out after an hour

What are you trying to calculate? Why can't ##h_2## be any height you like?
 
  • #5
Celso said:
That's all, the problem's statement is simply "the following picture represents the configuration of a falling objetc". It's actually a problem I tried to solve for another person but I couldn't figure out after an hour
There seem to only two constraints on the segment from B to C. The first is that the particle rests on the track, so the particle cannot fall any faster than if there was no track there. That would be a parabolic path and would give you a maximum value for h2.
The other constraint is that B appears to be an inflection point - with the path never again rising to meet the tangent line at point B. So at its highest, the B to C segment will follow just below that tangent line - giving the minimum value for h2.
 
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  • #6
@Celso :
Could you show us the entire problem as presented in the book?
It appears to be written in Portugese.
 
  • #7
.Scott said:
@Celso :
Could you show us the entire problem as presented in the book?
It appears to be written in Portugese.
yes, it's in portuguese. I don't have the file now (it's on my PC), apart from what I've written in my previous answer, it only asks to find:
•The velocity at B
•The x and y components of the velocity at B
•The height h2 knowing that the horizontal distance between B and C is 10m

The first two are elementar, maybe that's an indicator that there might be missing information
 
  • #8
PeroK said:
What are you trying to calculate? Why can't ##h_2## be any height you like?
because if the problem is consistent (which I'm not sure), ##h_{2}## can be written as function of the other given variables
 
  • #9
Celso said:
because if the problem is consistent (which I'm not sure), ##h_{2}## can be written as function of the other given variables

Unless the path from B to C is falling under gravity (no track), then there is no unique solution for the shape of the track from B to C, as @.Scott has said.
 

1. What is a particle in a roller coaster?

A particle in a roller coaster refers to a small object, such as a ball or a person, that is subject to the forces and motions experienced on a roller coaster ride.

2. How does the motion of a particle in a roller coaster change?

The motion of a particle in a roller coaster changes due to the forces acting on it, including gravity, normal force, and friction. As the roller coaster moves along the track, the forces and motions experienced by the particle will constantly change.

3. What is the relationship between velocity and acceleration for a particle in a roller coaster?

The velocity and acceleration of a particle in a roller coaster are directly related. When the velocity of the particle changes, its acceleration will also change. This is due to the forces acting on the particle, which can cause it to speed up, slow down, or change direction.

4. How does the height of a roller coaster affect the energy of a particle?

The height of a roller coaster affects the potential and kinetic energy of a particle. As the particle moves up and down the hills of the roller coaster, its potential energy will increase and decrease, while its kinetic energy will do the opposite.

5. What is the role of friction in the motion of a particle in a roller coaster?

Friction plays a significant role in the motion of a particle in a roller coaster. It can act as a resistance force, slowing down the particle's motion, or as a necessary force to keep the particle moving along the track. The amount of friction present will depend on the materials used on the roller coaster track and the speed of the particle.

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