[Irodov 1.65] Bar on top of a plank on a frictionless surface with a var. force.

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SUMMARY

The discussion focuses on the dynamics of a bar placed on a plank on a frictionless surface, subjected to a time-varying horizontal force F = at. The analysis reveals that until the force reaches the maximum static friction (F = km2g), both the bar and plank accelerate together. Once the static friction limit is surpassed, the plank continues with a constant acceleration while the bar accelerates further. The relationship between the accelerations of the plank (w1) and the bar (w2) is crucial for understanding the system's behavior over time.

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  • Understanding of Newton's laws of motion
  • Knowledge of static and kinetic friction concepts
  • Familiarity with basic calculus for analyzing time-dependent forces
  • Ability to interpret and draw acceleration vs. time graphs
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  • Study the effects of varying coefficients of friction on dynamic systems
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dharavsolanki
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A plank of mass m1 with a bar of mass m2 placed on it lies on a smooth horizontal plane. A horizontal force growing with time t as F — at (a is constant) is applied to the bar. Find how the acceler-ations of the plank w1 and of the bar w2 depend on t, if the coefficient of friction between the plank and the bar is equal to k. Draw the approximate plots of these dependences.
 
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I am discussing this question with a friend.

Initial Thoughts:

* The force is applied to the bar, the plank will experience the same force till a certain point.

* This point is actually when F = at becomes equal to the maximum static friction between the two masses.

* So, initially, till the static friction limit is reached, the bar will move along with the plank as a system, and after that, the plank will have a constant acceleration. While the bar will keep on accelerating.

The graphs will reveal something more. I am curious about the jump when F = km2g
 

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