Is acceleration still equal in the presence of air resistance?

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SUMMARY

In the presence of air resistance, heavier objects fall faster than lighter ones due to differences in terminal velocity. This phenomenon occurs because the gravitational force acting on heavier objects is greater, allowing them to overcome air resistance more effectively. The discussion highlights that while all objects fall at the same rate in a vacuum, air resistance significantly alters this behavior in real-world scenarios. The terminal velocity is reached when the force of gravity equals the drag force, which scales with the square of the velocity.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with the concept of terminal velocity
  • Basic knowledge of differential equations
  • Awareness of drag force and its relationship with velocity
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  • Study the principles of terminal velocity in fluid dynamics
  • Explore the mathematical modeling of drag forces using differential equations
  • Investigate the effects of varying densities on falling objects
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Physics students, educators, aerospace engineers, and anyone interested in the dynamics of falling objects and the effects of air resistance on motion.

  • #31
Yes M and m are factors, of course. Makes perfect sense and a bit of a duh moment there.

I was also heading where hmmm27 went in thinking about $$F={m}{a}$$ (or g instead of a if you want to be technical, sure o0)) to describe why without another force (air resistance) acceleration would be equal*. Doubling mass doubles force, yet that yields no change in acceleration: $$a=\frac{F}{m}$$

And of course this is essentially what A.T. said in post #14:
A.T. said:
Things fall the same way if the net force (sum of all forces) is proportional to mass:
- Gravity alone is proportional to mass.
- The sum of gravity and air resistance (which is independent of mass) is not proportional to mass.
*perhaps there's a question still remaining (for me, and perhaps others): is acceleration still equal in the presence of air-resistance up to the point of terminal velocity? Or does air resistance, being an opposing force to gravity, reduce acceleration slightly right 'from the get-go'?

It seems to me that we would then be discussing force subtraction, so relative magnitudes do matter. I.e. the heavier object has, for example, a downward force of 10, the lighter object 5, and the upward (resistive force due to air) is 2 at a given velocity (who cares about units?). For the heavier object, the net downward force is 10-2=8 (80% of the gravitational force). For the smaller object: 5-2=3 (60% of the gravitational force). Thus the smaller object's net force is further reduced proportional to mass at a given velocity.
Wrong, right, confused?
 
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