Why air resistance has less force than gravitation force in free fall?

Click For Summary

Homework Help Overview

The discussion revolves around the forces acting on an object in free fall, specifically comparing air resistance and gravitational force. Participants are exploring why air resistance is considered to have less magnitude than gravitational force during the initial phases of free fall.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are questioning the conditions under which air resistance is less than gravitational force, particularly in the context of an egg falling from a tree. There are inquiries about the effects of different scenarios, such as an updraft, and the implications of speed on air resistance. Some participants are also reflecting on the clarity and precision of the problem statement itself.

Discussion Status

The discussion is ongoing, with various interpretations being explored. Some participants have provided insights into the dynamics of free fall and terminal velocity, while others express frustration over the phrasing of the original question. There is no explicit consensus, but the conversation is delving into the nuances of the forces involved.

Contextual Notes

Participants are addressing potential misunderstandings in the problem statement and the importance of precise modeling in physics. The discussion includes considerations of initial conditions, such as the moment of release and the role of acceleration in determining net force.

Benjamin_harsh
Messages
211
Reaction score
5
Homework Statement
Why air resistance has less force than gravitation force in free fall?
Relevant Equations
net force is not equal to zero.
Why air resistance has less force than gravitation force in free fall?

If Egg is fall from a nest of tree, while falling, it has less magnitude of air resistance than gravitation force.
Where net force is not equal to zero.
 
Physics news on Phys.org
Benjamin_harsh said:
Problem Statement: Why air resistance has less force than gravitation force in free fall?
What research have you done on this? What have you found out?

If you open your palm vertically and swing your arm around, does air resistance overcome your arm's force? Why not?
 
Benjamin_harsh said:
Problem Statement: Why air resistance has less force than gravitation force in free fall?
Relevant Equations: net force is not equal to zero.

Why air resistance has less force than gravitation force in free fall?

If Egg is fall from a nest of tree, while falling, it has less magnitude of air resistance than gravitation force.
Where net force is not equal to zero.
Put the egg in a 100 km/hr updraft and see which wins out.
 
As soon as you release the egg (no updrafts) its acceleration is g. Instantaneously at the moment of release, the net force on the egg is equal to its weight and its speed is zero. There is no air resistance opposing the motion because there is no motion. As time increases
a. the speed will increase as long as there is non-zero acceleration but
b. increasing speed means increasing air resistance which implies that
c. the net force will be less than the weight nevertheless
d. the speed and hence the air resistance will keep increasing because there is still acceleration therefore
e. there will come a time when the speed is such that the air resistance has become large enough to equal the weight which makes the net force equal to zero.

At that time the falling egg has zero acceleration and its speed no longer changes, i.e. it has reached terminal velocity.

All this is neatly summarized with a differential equation $$m\frac{dv}{dt}=-mg+u(v)$$where ##v## is the speed of the falling object and ##u(v)## is a function of speed (usually a power law) such that ##u(0)=0##.
 
Benjamin_harsh said:
Problem Statement: Why air resistance has less force than gravitation force in free fall?
I don't know if you summarized or translated your original homework question, so interpret my comment accordingly.
However, it just drives me crazy when instructors ask questions like this that are untrue, incomplete, or misleading. Of course the students are confused, the question makes no sense. The solution to most all physics problems requires the student to be precise in how they model, evaluate, and solve the system or questions posed. How are they expected to learn this when they are set up this way?
 

Similar threads

  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 39 ·
2
Replies
39
Views
4K
  • · Replies 18 ·
Replies
18
Views
3K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 3 ·
Replies
3
Views
1K
Replies
28
Views
3K
  • · Replies 10 ·
Replies
10
Views
2K
Replies
17
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 31 ·
2
Replies
31
Views
4K