Determining a vehicle's translational acceleration from wheel torque

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Discussion Overview

The discussion revolves around determining a vehicle's translational acceleration from the torque applied at the wheels. Participants explore the relationship between wheel torque, vehicle mass, and the effects of wheel diameter and mass on acceleration. The scope includes theoretical reasoning and mathematical relationships relevant to vehicle dynamics.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant seeks to relate wheel torque to the translational acceleration of a vehicle, questioning how to incorporate vehicle mass into the calculations.
  • Another participant suggests that if the wheels do not slip, the velocity at the wheel's circumference equals the vehicle's velocity, implying that the number of wheels does not affect the basic calculation.
  • A participant emphasizes that the car's forward acceleration results from the friction force between the driving wheels and the road, proposing to use torque to find the tangential force at the wheel/road interface.
  • One participant confirms that dividing torque by the wheel radius yields the tangential force, which can then be used in the equation F=ma.
  • Another participant raises a concern about the problem potentially ignoring angular inertia effects due to the wheels, suggesting that this aspect may need to be considered in the calculations.

Areas of Agreement / Disagreement

Participants express differing views on whether the number of wheels affects the calculations and whether angular inertia should be considered. The discussion remains unresolved regarding the incorporation of these factors into the overall analysis.

Contextual Notes

There are unresolved questions about the assumptions regarding wheel slip, the treatment of angular inertia, and the overall impact of having multiple wheels on the calculations.

TB123
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Homework Statement



I am trying to figure out how to determine a vehicle's translational acceleration given a torque at the wheels so that I can determine what effect wheel diameter and mass will have on the ultimate translational acceleration.

Homework Equations



F = Ma

I*alpha = Torque

I = .5mr^2


The Attempt at a Solution



Torque = I*alpha = .5*m*a*r^3

a = (Torque*2)/(m*a*r^3)


I think I know how to find the translational acceleration of a rolling wheel, but how can I relate this to the total acceleration of a vehicle with a mass?

Also, there are 4 wheels (only 2 are supplied with a torque). Do I need to think about this as well?

Thanks for the help.
 
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You do not need to consider there being four wheels, if the wheels do not slip or slide then the magnitude of the velocity at the circumference of the wheel is the same as the velocity of the car.
 
How can I incorporate the mass of the vehicle in the equation?
 
The car's forward acceleration is due to the force of friction between the driving wheels and the road surface. The wheel pushes back on the road, the road pushes forward on the wheel where they meet. For the car, a = F/M.

Use your torque value to determine the tangential force at the wheel/road interface. This will be the same magnitude as the friction force (provided the wheels are not slipping). What's a formula for torque given the applied tangential force and the radius of the moment arm?
 
Ok, so just divide torque by the radius to get the force and then apply f=ma. That's easy enough.
 
TB123 said:
Also, there are 4 wheels (only 2 are supplied with a torque). Do I need to think about this as well?
This problem appears to be ignoring any angular inertia effects due to the wheels, since it doesn't include any information about the angular inertia of the wheels.

I see you already figured this out, but I'm unable to delete this message.
 

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