What is the angular momentum of uncle's tire immediately upon its departure?

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Homework Help Overview

The discussion revolves around calculating the angular momentum of a tire from a sports car, considering its mass, radius, and initial velocity. The problem is situated within the context of rotational dynamics and energy conservation principles.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants explore the calculation of angular momentum and kinetic energy, with some attempting to apply formulas for both translational and rotational motion. Questions arise regarding the correct application of parameters and the interpretation of the problem's conditions.

Discussion Status

Some participants have provided numerical results for angular momentum, while others express confusion about the calculations and the application of angles in the problem. There is an ongoing exploration of the correct approach to both parts of the question, with no clear consensus on the methods used.

Contextual Notes

Participants note the importance of distinguishing between the conditions of part (a) and part (b) of the problem, particularly regarding the angle of the embankment and the level road conditions for the tire's initial motion.

mattmannmf
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As you approached the I-74 exit in your uncle's little red sports car convertible you happened to notice a cat crossing the road. Not that you have any particularlove of cats (especially this one whose snooty disposition seems to beckon for a game of chicken) you swerve out of the way spilling scalding hot coffee all over your new summer duds.

Unknown to you at the time, the auto mechanic, having had an uneventful social life and being consequently somewhat incoherent, had inadvertently forgotten to fasten the lug nuts on one of your uncle's tires.

Given your velocity on the exit ramp as 2.8 m/s, a tire mass of 10 kg and radius 30 cm;

(a) What is the angular momentum of uncle's tire immediately upon its departure? (Assume the tire is a solid cylinder) in kg m2/s?


(b) Next, the tire cruises up an embankment at 30° for 1 meter beforelaunching across Piranha Lake. What is the velocity of the tire at the topof the embankment in m/s?

not sure where to start for this one
 
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i figured out that angular momentum is 4.2
 
Inital KE of the tire is 1/2*M*V2 + 1/2*I*(V/R)2; both rotational and translational
Final KE = Initial KE - M*g*h where h = 1m * sin(30°).

i just plugged in the numbers and got 2.42...wrong.
 
Hi mattmannmf! :smile:
mattmannmf said:
i figured out that angular momentum is 4.2

Nooo … how did you get that? :confused:
 
its rmvsin (30), i just plugged in the numbers and got 4.2...im sure its correct because it told me it was correct
 
mattmannmf said:
its rmvsin (30) …

No, the 30º is in part (b) …

this is for part (a), where the road is level …

you have the speed of the tyre, so what is the angular momentum?
 

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