DE for modelling motion of a box

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    Box Modelling Motion
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SUMMARY

The discussion centers on modeling the motion of a box sliding down a straight ramp using the differential equation ma = mg - kv, where 'ma' represents mass times acceleration, 'mg' is the gravitational force, and 'kv' denotes the force of friction. Participants clarify that 'k' is not the coefficient of kinetic friction (μ), but rather a constant related to air resistance, specifically k = 6πηr. The conversation emphasizes the importance of distinguishing between kinetic friction and the normal force component on an inclined plane.

PREREQUISITES
  • Understanding of Newton's second law of motion
  • Familiarity with differential equations
  • Knowledge of friction coefficients (static and kinetic)
  • Basic concepts of forces on inclined planes
NEXT STEPS
  • Study the derivation of forces on inclined planes
  • Learn about the role of air resistance in motion equations
  • Explore the relationship between friction coefficients and normal force
  • Investigate the application of differential equations in physics problems
USEFUL FOR

Physics students, mechanical engineers, and anyone interested in understanding the dynamics of motion involving friction and inclined planes.

acrusera
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So if you were to slide a box-like object down a straight ramp with a single gradient (its literally just an incline no curve). And you attempt to model it accurately would this be correct?
Given the DE
ma=mg-kv
where a=dv/dt, mg=force of gravity, kv= force of friction

Anyway my main question, is k the coefficient of kinetic friction? Does k=μ?
 
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What is µ according to you? Coefficient of static friction? then no ,k≠ µ
 
acrusera said:
So if you were to slide a box-like object down a straight ramp with a single gradient (its literally just an incline no curve). And you attempt to model it accurately would this be correct?
Given the DE
ma=mg-kv
where a=dv/dt, mg=force of gravity, kv= force of friction

Anyway my main question, is k the coefficient of kinetic friction? Does k=μ?

I think you've got your equations mixed up.

##ma = mg - kv##

Is for a body falling under gravity with air resistance proportional to its velocity.
 
PeroK said:
Is for a body falling under gravity with air resistance proportional to its velocity.
k=##6 \pi \eta r## ??
then what about the ramp?
 
The "coefficient of friction", \mu is the number that multiplies the normal force on an object to give the friction force. An object of mass m, has weight mg. On a ramp making angle \theta with the horizontal, we can divide the weight into components parallel to and normal to the ramp. The component normal to the ramp is mg cos(\theta).
 

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