Using mathematica to solve ferris wheel problem

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Discussion Overview

The discussion revolves around a physics homework problem involving a Ferris wheel and a rescue boat. Participants are attempting to determine the correct angle at which a stunt person should jump off the Ferris wheel to land safely in the boat as it approaches. The problem includes considerations of angular velocity, position calculations, and the timing of the jump.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant reports obtaining a result of 240 degrees for the jump angle, which contradicts the expected range of 90 to 180 degrees.
  • Another participant suggests verifying the output values for various angles to ensure the equations are implemented correctly.
  • Code snippets are shared to illustrate the calculations being performed, including the definitions of position and velocity functions based on the angle.
  • Concerns are raised about the correctness of the results for angles other than zero, with one participant expressing difficulty in identifying errors in their code.
  • There is a discussion about the structure of the Mathematica code, with one participant questioning the syntax used for defining functions.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correctness of the results or the implementation of the code. There are multiple competing views regarding the accuracy of the calculations and the interpretation of the results.

Contextual Notes

Some participants express uncertainty about the correctness of specific values and the structure of the code. There are unresolved questions about the outputs for angles other than zero and the implications of the coding approach used.

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Homework Statement


Consider a large Ferris wheel above a lake. The wheel is 30 meters in radius and its center stands 80 meters above the lake level. At t = 0, a stunt person stands on the top of the Ferris wheel (theta=0) which is rotating at a constant angular velocity w = 0.2 rad/s. At t = 0, a rescue boat is 150 m from the vertical center line of the Ferris wheel and travels toward the base of the wheel at a constant speed of 10 m/s.(In other words, if the center of the wheel has coordinates (0, 80) and the initial coordinates of the person are (0, 110), the initial position of the front of the boat is (150, 0)). Assume the person has no initial velocity other than that of the rotating wheel; assume also that there are no sources of friction in this problem. Assume further that the boat is one meter in length and the long axis of the boat is moving directly toward the Ferris wheel. The Ferris wheel is rotating toward the incoming boat.Your program will allow you to determine when should the stunt person step off the Ferris wheel to safely land in the boat as it speeds by. At what angle (with respect to the vertical) should the person step off to accomplish this?

Homework Equations


http://www.luc.edu/faculty/dslavsk/courses/phys301/classnotes/projectequations.pdf

These are the relevant equations I used to produce my programming code

The Attempt at a Solution


I have attached my mathematica program. I am getting a result of 240 degrees, however, we are told that the correct angle should be between 90 degrees and 180 degrees. Can anyone help me out here?
Thank you
 

Attachments

  • mathematica project 1.PNG
    mathematica project 1.PNG
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At the end of the document you link, you have a table with some results. Have you checked that for a given θ on input, you get the correct values using your equations?

It would also be helpful if you pasted your code in a post. It is hard to work with a picture.
 
DrClaude said:
At the end of the document you link, you have a table with some results. Have you checked that for a given θ on input, you get the correct values using your equations?

It would also be helpful if you pasted your code in a post. It is hard to work with a picture.

I tested the angle zero and I do get the correct values. Here is my code pasted. Thank you for your reply

Clear[g, \[Omega], R, H, h, Vb, \[Theta], Pxo, Pyo, Vxo, Vyo, Ta, Tw, \
Ttotal, Bx, P, nterms]
g = 9.8; \[Omega] = .2; R = 30; H = 80; h = .01; Vb = 10;
\[Theta][n_] := n*h;
Pxo[n_] := Px[n] = R*Sin[\[Theta][n]];
Pyo[n_] := Pyo[n] = H + R*Cos[\[Theta][n]];
Vxo[n_] := Vxo[n] = \[Omega]*R*Cos[\[Theta][n]];
Vyo[n_] := Vyo[n] = -\[Omega]*R*Sin[\[Theta][n]];
Ta[n_] := (Vyo[n] + Sqrt[Vyo[n]^2 + 2*g*Pyo[n]])/g;
Tw[n_] := \[Theta][n]/\[Omega];
Ttotal[n_] := Tw[n] + Ta[n];
Bx[n_] := Bx[n] = 150 - (Vb*Ttotal[n]);
P[n_] := P[n] = Vxo[n]*Ttotal[n] + Pxo[n];
nterms = Catch[Do[If[(Bx[n] - P[n]) < 0, Throw[n]], {n, 1000}];
Throw[0]];
Print["Jump at ", (\[Theta][nterms]) (180/\[Pi]), \[Degree]]
 
uxdf700 said:
I tested the angle zero and I do get the correct values.
That's not enough. Test for all angles given in the table.
 
DrClaude said:
That's not enough. Test for all angles given in the table.
I tested the other angles and I am not getting the correct answer. I am having trouble finding the error in my coding
 
uxdf700 said:
I tested the other angles and I am not getting the correct answer. I am having trouble finding the error in my coding
Which values are incorrect?
 
The Tair and position of the person P and of the boat Bx at all angles that are not 0.
 
uxdf700 said:
The Tair and position of the person P and of the boat Bx at all angles that are not 0.
That's strange, because this is not the same thing I got when I tried it. (I don't have access to Mathematica right now).

I can't check if this is the source of the problem, but the way you wrote things is a bit strange. For instance:
P[n_] := P[n] = Vxo[n]*Ttotal[n] + Pxo[n];

Why do you have "P[n]=" after "P[n_] :=" ? I've never seen this in Mathematica, but I'm not a specialist.
 
I wrote it like this because later on in the code I need to use these functions to define other functions. I don't think it works otherwise
 

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