Falling question about terminal velocity

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Discussion Overview

The discussion revolves around the concept of terminal velocity, particularly in the context of free fall from an airplane. Participants explore the implications of terminal velocity on the impact force experienced when hitting the ground, as well as the factors that influence terminal velocity, such as mass, shape, and air resistance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant initially states that terminal velocity is 9.81 m/s, confusing it with the acceleration due to gravity.
  • Another participant clarifies that terminal velocity varies depending on the object's weight and that the effect of a falling object colliding with a wall can be described by its momentum (9.81 × mass).
  • There is a mention of a demonstration where two objects of different masses fall at the same rate, highlighting that mass does not affect the rate of fall when air resistance is negligible.
  • Further elaboration is provided on how terminal velocity is reached when air resistance balances the gravitational force, and that terminal speeds differ based on an object's size, shape, and mass.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the initial misunderstanding of terminal velocity versus gravitational acceleration. There is a general agreement on the factors affecting terminal velocity, but the discussion remains unresolved regarding the implications of terminal velocity on impact force.

Contextual Notes

The discussion highlights the importance of distinguishing between terminal velocity and gravitational acceleration, as well as the role of air resistance in free fall scenarios. There are assumptions about neglecting air resistance in certain demonstrations that may not apply in all cases.

Robertmunch
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Hey guys I have a question.

Terminal velocity is 9.81mps correct? Which converts to basically 35kmph so does that mean hitting the ground from free fall after jumping out of an air plane would have the same effect as hitting a wall or something immobile and hard at 35kmph?

Thanks
 
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Terminal velocity is not 9.81 m/s, it is the acceleration due to gravity that is 9.81 m/s^2. The terminal velocity acquired depends on the weight that is falling out of the airplane.
But in the case that there is some arbitary object with terminal velocity 9.81 m/s, the effect of having it fall to the ground and having it collide with an immobile wall, will be the same; the momentum imparted will be 9.81×mass in both cases.
 
Oh I had a brain fart I guess. I thought I remembered a demonstration from physics class where the teach dropped 2 objects of different mass and they both hit the ground at the same time (obv the shape of the object would make a difference because of air resistance)
 
Robertmunch said:
Oh I had a brain fart I guess. I thought I remembered a demonstration from physics class where the teach dropped 2 objects of different mass and they both hit the ground at the same time (obv the shape of the object would make a difference because of air resistance)
The experiment was to demonstrate that all objects (at the same distance above the Earth's surface) will fall at the same rate regardless of their mass, assuming that you can neglect air resistance. Objects are chosen so than the effect of air resistance is negligible over the fall.
Terminal velocity occurs when air resistance comes into play. It is determined by the the relationship between an object's size, shape and mass. Air resistance increases with velocity, so as the falling object accelerates, the air resistance increases, at some point the air resistance equals the force of gravity trying to accelerate the object, it has reached terminal velocity and just continues to fall at a set speed. Because of the above mentioned factors, terminal speeds for various objects can vary greatly. ( the terminal speed for a ball bearing will be greater than that of a feather even if they had the same mass).
 

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