Gravity?

[ThisIsMe]

Doesn't anyone know?

Aerodynamics have to be taken into account. A stick of gum in a wrapper and all won't fall as a round ball of gum would.

Well, I sort of thought of that and tried to come up with two items that wouldn't have a lot of difference in "drag."
So my original question was to see if mass changes the action of gravity, and I'm guessing the answer is no?

Well, an objects mass would determine its gravity, and also its terminal velocity, but if the object is larger, it could mean more surface area and thus more drag.

A better question is, if you had two balls of identical size, one made of lead and one made of styrofoam, the lead ball would fall faster. While both objects would have the same drag, because they are the same size, and the same surface area, the lead ball has more mass and density, and thus a higher gravity yield and a higher terminal velocity.

 

[ThisIsMe]

If you drop a man's wristwatch and a piece of bubblegum from the top of the Empire State Building at exactly the same time, which one hits the ground first?

Depends on how they are shaped. In a vacuum they would hit at the same time. But the Empire State Building is surrounded by air. If a great big bubble has been blown in the bubble gum, the bubble will act as a parachute.

But my experiment did not have a big bubble blown in the gum. What would work, I guess, to test this out, would be if I had two items of identical size and shape that were made of two materials such as a ping pong ball and an identically sized ball of lead.

You did not say whether it did or did not... until now.

The air friction would have much more effect on the ping pong ball because the ping pong ball is less dense. The air friction would have hardly any effect on the ball of lead from that height compared to the effect the air friction has on the ping pong ball.

I don't understand that. Why should the friction be any different if they are exactly the same size and shape? Both totally smooth on the outside.

The lead ball, having a higher mass and density, has a stronger pull of gravity, and can overcome the resistance of air to achieve a higher terminal velocity.

 

[ReinyDays]

Well, I sort of thought of that and tried to come up with two items that wouldn't have a lot of difference in "drag."
So my original question was to see if mass changes the action of gravity, and I'm guessing the answer is no?

This may have been answered already ... but I yarded up some of that fake moon landing footage from the giant vacuum chamber NASA built in Hollywood, California:



If I remember correctly, this shot made into their weekly reality show ...

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The answer is YES ... changes in mass make changes in gravity ... there's a catch here ... as the video shows, acceleration is constant and independent of mass ... ah, but gravity is a force, and that force directly depends on mass ...

Consider a 1 inch sphere of tungsten and one of aluminum ... very different masses ... they will fall through the vacuum at exactly the same rate ... but the more massive tungsten will make a much deeper dent in the ground ... same acceleration and speed, very much different force upon impact ...

 

[Wuwei]

Nobody posted the proof that two objects always have the same gravitational acceleration in a vacuum.

Suppose an object has mass and you put force on it, use this equation to find acceleration:
F =ma (Force = mass x acceleration. m is the “inertial mass” )

Suppose a planet has mass M, and the object has mass m (Here, m is the "gravitational mass".)
F= GmM/d² (Inverse square law for gravitational force)

Equate the two forces
ma = GmM/d²

The mass of the object cancels out.
a = GM/d²

Acceleration due to gravity is independent of the object mass. Acceleration only depends on the gravitational constant G, the mass of the planet M, and the distance.

The fundamental equivalence of the inertial mass and gravitational mass led to the general theory of relativity.
.

 

[ReinyDays]

Here's another fake NASA film from a few centuries from now:



Sounds simple to me ...

 

[Asclepias]

If you drop a man's wristwatch and a piece of bubblegum from the top of the Empire State Building at exactly the same time, which one hits the ground first?

Depends on which one is heaviest. In reality chaos theory would say that it couldnt be predicted.

 

[WorldWatcher]

Nobody posted the proof that two objects always have the same gravitational acceleration in a vacuum.

Suppose an object has mass and you put force on it, use this equation to find acceleration:
F =ma (Force = mass x acceleration. m is the “inertial mass” )

Suppose a planet has mass M, and the object has mass m (Here, m is the "gravitational mass".)
F= GmM/d² (Inverse square law for gravitational force)

Equate the two forces
ma = GmM/d²

The mass of the object cancels out.
a = GM/d²

Acceleration due to gravity is independent of the object mass. Acceleration only depends on the gravitational constant G, the mass of the planet M, and the distance.

The fundamental equivalence of the inertial mass and gravitational mass led to the general theory of relativity.
.

Thank you. That is along my previous statements. That people confuse the "force" of gravity with gravitational acceleration. The acceleration impacts energy into an object which I think of kinetic energy (mass moving through space). The kinetic energy built up during acceleration is represented as a force, but the "force" (attraction) of gravity manifests itself as acceleration. This "force" of gravity acts on a body in a uniform manner regardless of mass - the acceleration factor is the same - the bodies actual acceleration various based on other factors. What changes in the kinetic energy.

The answer to the OP's question remains. The watch would hit first, not because gravity represented as an acceleration factor in the Terminal Velocity formula - acts differently, but because OTHER factors for the object in the atmosphere retard the effects of acceleration.

Brian Cox visits the world's biggest vacuum | Human Universe - BBC

Here is an excellent video that shows what I mean. And here is the source website -->> Dropping Objects in World's Largest Vacuum Chamber
.
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.WW

 

[Fort Fun Indiana]

That people confuse the "force" of gravity with gravitational acceleration.

You are the one who is confused. The acceleration of a massive object is the definition of force. When that acceleration is due to gravity, that is the definition of gravitational force.

 

[ReinyDays]

That people confuse the "force" of gravity with gravitational acceleration.

You are the one who is confused. The acceleration of a massive object is the definition of force. When that acceleration is due to gravity, that is the definition of gravitational force.

Acceleration and force are two different things ... they're proportional, but not equal ...

 

[Fort Fun Indiana]

That people confuse the "force" of gravity with gravitational acceleration.

You are the one who is confused. The acceleration of a massive object is the definition of force. When that acceleration is due to gravity, that is the definition of gravitational force.

Acceleration and force are two different things ... they're proportional, but not equal ...

I did not say or imply they are equal. I said acceleration of a massive object is the definition of force.

F=ma

You can measure the force by measuring the mass and acceleration of the object.

"Force" is a term we use to describe the phenomenon of a massive object accelerating. When we know force is being applied to a massive object, yet it is not accelerating, we don't scratch our heads and question the definition of force. We look for another force which counteracts the first force. Such as, friction, or wind, or gravity.

And when a massive objects remains at rest ( or at any constant velocity, more comprehensively), even if there are 100 different forces acting upon it, the net force on the object is zero. Because: F=ma

Would you call that,"intuitive"? I wouldn't.

 

[ReinyDays]

You're claiming no one in the entire world has ever been confused by this? ... I think WW is right, there are people who don't understand these distinctions ...

 

[Fort Fun Indiana]

You're claiming no one in the entire world has ever been confused by this? ... I think WW is right, there are people who don't understand these distinctions ...

Of course people can be confused by this. If not, then we wouldn't need scientists, or research,or laws of physics,now would we?

Scientists are STILL confused by quantum mechanics. But they are compelled by the mathematics and research to accept the basic principles, no matter how counter-intuitive they are.

WW may be right about a lot of things. But the topic of gravity as a force is not one of them. For example:

"A feather sitting next to a 2-ton slap of steel has the same force of gravity applied to it. " - WW

That is 100% incorrect and flies right in the face of the singular, watershed discovery by Newton regarding gravity.

If the steel slab has 1,000,000 times the mass of the feather, then the force of gravity on it, all else equal, will be precisely 1,000,000 times the force of gravity on the feather. Simple and elegant. But...intuitive? Not really.

If we all just understood this intuitively, then we would not have to have waited until the 1600s for someone to come along and empirically discover it, now would we have?

 

[Rye Catcher]

If you drop a man's wristwatch and a piece of bubblegum from the top of the Empire State Building at exactly the same time, which one hits the ground first?

They SHOULD hit the ground at the same time.

If the bubble gum is released with a large bubble, it might rise before it falls. Wind speed too would likely slow the descent of the bubble gum, especially if it was released as a bubble.

 

[Fort Fun Indiana]

If you drop a man's wristwatch and a piece of bubblegum from the top of the Empire State Building at exactly the same time, which one hits the ground first?

They SHOULD hit the ground at the same time.

If the bubble gum is released with a large bubble, it might rise before it falls.

* If and only if there is an updraft

 

[ReinyDays]

So ... then you agree with WW that people get confused by these non-intuitive ideas? ...

 

[Fort Fun Indiana]

So ... then you agree with WW that people get confused by these non-intuitive ideas? ...

Absolutely!

 

[Fort Fun Indiana]

Ask anyone new to physics the following question:

Consider a block on a surface. Put a bear on one side and a lion on the opposite side. Have each push on the block with 100 N of force. What is the net amount of force being applied to the block?

They will answer 200 N, every time. The correct answer is: 0 N, in certain contexts.

I left out a lot of specifics, such as the acceleration being the measure of the acceleration of the center of gravity of the block, and therefore same for the measure of force on the center of gravity of the block, etc

 

[Fort Fun Indiana]

Also counterintuitive:

The center of gravity of a system is a dimensionless point. Such a thing would only seem to exist "on paper". Yet we can use this concept to describe the behavior of systems, such as the Earth-Sun relationship. Isolating this system shows us that the Earth does not revolve about the center of gravity of the Sun. Both objects revolve about the center of gravity of the Earth-Sun pair. This point can never be "found" and collected or marked. It can only be described mathematically.

 

[Fort Fun Indiana]

This may have been answered already ... but I yarded up some of that fake moon landing footage from the giant vacuum chamber NASA built in Hollywood, California:

ReinyDays

Fascinating! And how did they manage to reduce the gravity in this vacuum chamber, as evidenced by the slower acceleration of the dropped objects and the astronauts, as they return to the surface after hopping, as compared to the acceleration of Earth's gravity? How are the astronauts able to hop so high, with a minimum of effort? Why does the regolith dust fly up so high, then fall more slowly than it would on earth, with each footstep of the astronauts? If this soil is so loose, why aren't the astronauts sinking further into it? Why did the astronaut appear not to tire quickly, when holding a hammer at arm's length?

These goofy nutball conspiracy theories raise more questions than they answer.

 

[RandomPoster]

If you drop a man's wristwatch and a piece of bubblegum from the top of the Empire State Building at exactly the same time, which one hits the ground first?

They should both hit the ground at the same time.

In the absence of air resistance, a feather and a bowling ball would hit the ground at the same time. With air resistance, the maximum falling speed becomes dependent on the amount of mass in relation to its amount of surface area, as well as the aerodynamic design of the object. The same concept holds in rifle ballistics, which is why the best shooters in the world don't use lightweight, low sectional density bullets in long range shooting contests when they have a choice of cartridge. For example, 1,000 yard bench rest competitions in categories that allow any cartridge are dominated by .30 caliber magnums. The longest kills made by military snipers in excess of a mile and a half are made with cartridges like a .50 BMG, not a .223 Remington.