Challenging Classical Mechanics Problems: Can You Solve Them?

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Discussion Overview

The discussion revolves around challenging classical mechanics problems, specifically focusing on the dynamics of objects on an incline with kinetic friction and the application of d'Alembert's principle in non-inertial frames. Participants seek assistance in solving these problems and share their approaches and equations.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant presents equations for calculating distance and time for an object moving up and down an incline with kinetic friction, specifying the conditions for final velocity and acceleration.
  • Another participant introduces d'Alembert's principle, discussing the dynamics of a non-inertial frame and the need to add a fictitious force to analyze the system equivalently.
  • A participant expresses gratitude for the help received and mentions ongoing difficulties with problems that lack specific values.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the solutions to the problems, and multiple approaches are presented without resolving the challenges faced.

Contextual Notes

Some problems discussed lack specific values, which may complicate the application of the proposed solutions and equations.

johnherald
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Hello i have the difficulty in solving this two problems..thank you for your help math help boards :-) View attachment 8748
 

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1.6

distance up the incline (with kinetic friction present) ...

$\Delta x = \dfrac{v_f^2 - v_0^2}{2a}$

time up the incline ...

$t = \dfrac{v_f-v_0}{a}$

... where $v_f=0$ and $a = -g(\sin{\theta} + \mu \cos{\theta})$time down the incline ...

$\Delta x = v_0 \cdot t + \dfrac{1}{2}at^2 \implies t = \sqrt{\dfrac{2\Delta x}{a}}$

note $v_0 = 0$, $\Delta x$ is the opposite of that found going up the incline and $a = -g(\sin{\theta} - \mu \cos{\theta})$
 
1.5 is related to d'Alembert's principle. We can analyze the dynamics of an accelerating frame of reference (i.e non-inertial) by adding a fictitious force. Since the force in system A is $m*100$, then a fictitious force of $m*10$ must be added to system B so that the dynamics in both systems are equivalent.
 
thanks a lot that will help me solving the other problems similar to that two particular question...:-)
and i have the difficulty solving some problems specially to the questions without a value.. thank you again for your help..
 

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