Don't objects in free fall always experience one g?

In summary, the article discusses Joseph Kittinger's record-breaking skydive, which stated that he experienced a G force of 22 m/s^2. While objects in free fall typically experience practically zero g, the article explains that the acceleration experienced from the parachute at opening can increase the g force. The reference to paragraph 3 in the article also clarifies that the acceleration mentioned is due to rotation, not vertical acceleration.
  • #1
mr.physics
21
0
I recently read an article about Joseph Kittinger which stated that in a skydive, he was subjected to a G force of 22 m/s^2. Disregarding fluid resistance, don't objects in free fall always experience one g?
 
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  • #2
You can get a higher amount of g's when you open your chute. And 22 m/s² is barely over 2 g's.
 
  • #3
Could you please explain why?
 
  • #4
Because the chute is pulling you up.
 
  • #5
mr.physics said:
I recently read an article about Joseph Kittinger which stated that in a skydive, he was subjected to a G force of 22 m/s^2. Disregarding fluid resistance, don't objects in free fall always experience one g?

No, objects in freefall experience practically zero g. That's kind-of the definition of freefall.

Can you link to or reference the article? Or cut and paste the line containing that statement, along with enough text to put it in context?
 
  • #6
It must be referring to the acceleration experienced from the parachute at opening, as velocity decreases about 50 m/s.
 
  • #8
Zero G in free fall. One G upwards at rest on Earths surface at sea level. For the skydiver, <1G in the aircraft, 0G in free fall, ~4-5G at parachute opening, >1G on landing, 1G on the ground.
 
  • #9
Zero G in free fall.
Why?
 
  • #10
G-force is your acceleration relative to free fall. 0G is free fall is weightlessness.
 
  • #11
Neglecting drag of course, in the case of the skydiver.
 
  • #12
So an object experiencing a G force of 1 G is acclerating at 19.6 m/s^2?
 
  • #13
Isn't 1G 9.8 ms-2?
 
  • #14
Free Fall is just acceleration by gravity. However, the parachutist is also experiencing an acceleration by the opening of the parachute as mentioned (To slow down the speed of descent). If you add up the 2 accelerations (by vector addition) the acceleration is greater than the acceleration due to gravity.

And I think blkqi meant -1G experienced on when we are on the ground, so we have a net acceleration of 0.
 
  • #15
simpleton said:
And I think blkqi meant -1G experienced on when we are on the ground, so we have a net acceleration of 0.
No. What blkqi means is that if you measure acceleration using an accelerometer then you find that free-falling objects have 0 acceleration and an object at rest on the ground has an acceleration of g upwards. This is the acceleration that an object "feels".
 
  • #16
1G on the ground. You can think of g-force as the vector difference between the acceleration relative to the field and the acceleration experienced during free-fall, relative to the magnitude of free fall acceleration.

Thus in free-fall:
[tex]\frac{-9.8-(-9.8)}{|-9.8|}=0G[/tex]

And on the ground:
[tex]\frac{0-(-9.8)}{|-9.8|}=1G[/tex]
 
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  • #17
According to the usage of this acticle, http://en.wikipedia.org/wiki/Free_fall#Record_free_fall", quoted above, "free fall" is the following:

"Near sea level, an object in free fall in a vacuum will accelerate at approximately 9.81 m/s2, regardless of its mass."

and

"Record free fall

Joseph Kittinger starting his record-breaking skydive. According to the Guinness book of records, Eugene Andreev (USSR) holds the official FAI record for the longest free-fall parachute jump after falling for 80,380 ft (24,500 m) from an altitude of 83,523 ft (25,460 m) near the city of Saratov, Russia on November 1, 1962. Though later jumpers would ascend higher, Andreev's record was set without the use of a drogue chute during the jump."

They imply that Free Fall in air occurs throughout the fall, and includes terminal velocity, where air drag exerts a balancing upward acceleration of nearly 1g. I say nearly one g because the diver slightly decelerates as the air thickens.
 
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  • #18
mr.physics said:
http://en.wikipedia.org/wiki/Free_fall#Record_free_fall
paragraph 3


At sea level on Earth do objects not fall at approximately one g?

Paragraph 3 is talking about accleration due to an object in rotation. The article,

"(he went into a flat spin at a rotational velocity of 120 rpm; the g-force at his extremities was calculated to be over 22 times that of gravity, setting another record)."

--nothing to do with the vertical acceleration.
 

1. Why do objects in free fall experience one g?

Objects in free fall experience one g because of the force of gravity. Gravity is a fundamental force of nature that pulls objects towards each other. On Earth, gravity causes objects to accelerate towards the ground at a rate of 9.8 meters per second squared, which is equivalent to one g.

2. Can objects in free fall experience more or less than one g?

Yes, objects in free fall can experience more or less than one g depending on the strength of the gravitational force acting on them. For example, on the moon where the gravitational pull is weaker, objects will experience less than one g in free fall. In contrast, on a planet with a stronger gravitational pull, objects will experience more than one g in free fall.

3. Is the acceleration of objects in free fall always constant?

Yes, the acceleration of objects in free fall is always constant (9.8 meters per second squared on Earth) as long as there are no other forces acting on the object, such as air resistance. This means that the velocity of the object is increasing at a constant rate as it falls towards the ground.

4. Do objects in free fall experience one g in all locations on Earth?

No, objects in free fall do not experience one g in all locations on Earth due to variations in the strength of gravity at different locations. Factors such as altitude, latitude, and local topography can affect the strength of gravity and therefore the acceleration experienced by objects in free fall.

5. How does air resistance affect the acceleration of objects in free fall?

Air resistance can affect the acceleration of objects in free fall by slowing down their descent. As objects fall through the air, they experience a force opposite to their direction of motion due to air resistance. This force increases with the speed of the falling object, eventually reaching a point where it is equal to the force of gravity, resulting in a constant velocity or terminal velocity. This means that the object will no longer accelerate and will fall at a constant speed until it reaches the ground.

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