/sci/ - Science & Math

[onepack No.3092013]

Good evening/morning, /sci/. I am ashamed to ask you a basic newtonian physics question, it goes without saying that your anwsers are greatly appreciated.

Would a steel ball fall as fast as a paper ball if dropped from 8000 feet? No wind, both same shape and volume. Theorical case with normal Earth conditions, normal air resistance.

wouldn't the mass of the earth be so huge that it would attract both objects roughly with the same force, therefore, hitting it at the same time?

[Anonymous No.3092019]

No, things that are heavier fall faster. Ever seen a car float to the ground? Nope.

[onepack No.3092030]

> things that are heavier fall faster.
>this is /sci/, elaborate.

[Anonymous No.3092032]

actually, the steel ball will fall slower. you are correct in saying that the mass of the earth is so huge it will attract objects with the same force. now consider that f=ma (force equals mass times acceleration, one of newtons laws). for the force to be the same for an object with a greater mass, the acceleration must be smaller. so objects with greater mass will, counterintuitively, fall slower. the reason they tend to fall faster in real life is because in real life they DO have different shapes, volumes and air resistance

[Anonymous No.3092033]

>>3092030
Weight is a force, a measure of mass times gravity. The greater the mass, the greater the force downwards, hence a greater speed.

[Anonymous No.3092038]

No. Steel ball would fall faster.

If you want paper ball to fall faster you would have to make it considerably more massive.

[Anonymous No.3092040]

>>3092030
He's trolling you son.
If the objects are the same shape, volume surface area etc. they fall at the same speed.
More massive object = more attraction to Earth force, but also more resistant to acceleration
Less massive = less attraction to Earth, but also less resistant to changes in motion

[Anonymous No.3092044]

>>3092038
wrong. OP said to negate air resistance and volume, etc. given that, a lighter object will fall faster. basic newtons law, f=ma. the earth always attracts with the same force (which is why you don't feel a difference in gravity whether you're small or large or short or tall), so the acceleration goes down with increased mass.

[Anonymous No.3092050]

>>3092013
>>Theorical case with normal Earth conditions, normal air resistance.

if youre conditions specify air resistance, then the steel ball will descend faster to the surface

[Anonymous No.3092053]

http://en.wikipedia.org/wiki/Galileo%27s_Leaning_Tower_of_Pisa_experiment

[Anonymous No.3092063]

>>3092040
He is right, you are being trolled. The acceleration of gravity for every object is roughly 9.8 /s^2. It isn't because the mass of earth is so large though. When calculating for the acceleration due to gravity using newton's law of gravitation the mass of the object cancels out. Thus the mass of the falling object is not relevant to the acceleration caused by gravity.

I learned this in highschool.

[Anonymous No.3092061]

>>3092044
OP said normal air resistance.

[Anonymous No.3092058]

>>3092040
>implying i could drop a cotton ball and a ball bearing next to each other and they would fall at the same speed
2/10. One point for a weak explanation, one point for trying to subvert him by saying the others are trolling.

[Anonymous No.3092066]

>>3092063
This is without air resistance.

[Anonymous No.3092073]

>>3092044

>>Would a steel ball fall as fast as a paper ball if dropped from 8000 feet? No wind, both same shape and volume. Theorical case with normal Earth conditions, normal air resistance.

Wrong. OP didn't say to "negate air resistance and volume, etc."

Thread is full of idiots teaching other idiots how to read shit incorrectly.

I'm so mad.

[Anonymous No.3092076]

>>3092061
>implying OP didn't say "No wind", ie no air resistance.

[Anonymous No.3092098]

this thread is filling my brain with fuck

[onepack No.3092109]

OP here, can you confirm that TWO IDENTICALLY SHAPED OBJECTS (=same shape and volume) with different masses and density, would hit the ground at a different time if dropped from the same distance at the same time WITH AIR RESISTANCE????

[Anonymous No.3092110]

OP's conditions were:
1. no wind
2. air resistance
Like on a day with no breeze, and whatnot.

[Anonymous No.3092118]

well if the same mass, think of something: g is an acceleration, that applies to every object near the planet. So either way, the object will be accelerated at g.

[Anonymous No.3092124]

>>3092118
right, sort of, but in the conditions stated, aerodynamics comes into play

[onepack No.3092126]

OP here. Can someone explain why if the mass of the earth is so huge why wouldn't it attract both objects roughly with the same force, therefore, hitting it at the same time?

[Anonymous No.3092138]

>>3092126

your question is vague, try restating it

[Anonymous No.3092142]

>>3092126
It does attract it with the same force.
F=MA, as explained above.
Force=Mass*Acceleration

Let's say we have two masses. 1kg, and 2kg for simplicities' sake. And we have a force of 10 newtons (again, simplicity). So we have:

10=1*A (so the 1kg will accelerate at 10m/s/s)
10=2*A (so the 2kg will accelerate at 5m/s/s)

A heavier object will fall slower, negating air resistance, etc.

[Anonymous No.3092161]

>>3092126
You should understand that the mass of paper ball is much smaller than that of a steel ball.

They would fall with the same speed in vacuum, but since you said normal air pressure, then steel ball has more mass for the same surface area, that meets air resistance, and therefore falls faster.

[Anonymous No.3092166]

>>3092063
ITT: Trolls trolling trolls trolling trolls.
>implying the earth's mass has nothing to do with gravity

MASS IS WHAT GIVES THINGS GRAVITY, FUCKTARD. Christ, everybody here except >>3092032 is retarded

[Anonymous No.3092191]

>>3092032
>>3092166
troll trolling trolls trolling trolls trolling trolls.

[Anonymous No.3092193]

>>3092109
steel ball has mass greater than the mass of air beneath it, meaning it's not as affected by it as a paper ball. paper balls' mass is lower so the mass of air it encounters while falling will slow it down.

[mtp !HjLTtX.XQ2 No.3092203]

>>3092166
not strictly true

[Anonymous No.3092219]

>>3092193
>steel ball has mass greater than the mass of air beneath it, meaning it's not as affected by it as a paper ball
Complete and utter bullshit. I can stab a diamond with a knife and it won't do shit. I can then stab a much heavier car and it'll scratch the fuck out of it. Mass has nothing to do with how much one object affects another

[onepack No.3092238]

Op here.
I appreciate your imput, but I am getting contradictory answers.
1.Why wouldn't they hit the ground at the same time if the Mass of the earth is so huge in relation to their specific masses?
2.Would the heavier object really fall slower as it encounters more air resistance?

[Anonymous No.3092258]

>>3092238
1. The earth is HUGE. It attracts everything with the same force, yeah? What you have to realise is that force does not equal speed. A force is something else entirely. So while it attracts masses with the same FORCE, they will not travel the same SPEED. See >>3092142

2. Yes and no. In real life, heavy objects fall faster than light objects because they tend to face less air resistance (eg think of a ball bearing vs a cotton swab. Could be the same size, but one is wispy and has a greater surface area), aren't as vulnerable to wind, etc. In a vacuum, however, a heavier object will fall slower than a light one

[onepack No.3092282]

>>3092258
thank you kind sir, this was the answer I was expecting all along. Notice I stated same shape (= identical surface) and No Wind.
>Therefore, paper ball hits the ground later.

[Anonymous No.3092290]

>>3092258
wtf stop saying shit please. If we neglect aerodynamics, an object with a mass m and another with a mass 2m will NOT be attracted with the same force.
If the first is attracted with the force F, the second will be attracted with the force 2F.
And, therefore, they will go at the same speed if they started at the same speed. /thread

[Anonymous No.3092295]

>>3092282
I hope you didn't believe that guy, or you just can stop trying to do physics.

[Anonymous No.3092297]

>>3092238

Mass =/= Air resistance.

In a completely static air column, with non-deformable weights of equal shape and volume then yes. They will hit the ground at the same time.

In your example the paper-ball would be deformed somewhat due to its low mechanical strength, creating turbulence and slowing its rate of fall. In YOUR example, the metal ball would land first.

If we grant that the Paper Ball was non-deformable then the two objects will reach the earth simultaneously.

[Anonymous No.3092305]

>>3092282
He is fucking lying to you about that part.

>In a vacuum, however, a heavier object will fall slower than a light one.

Think about it a bit. Let's imagine earth with its atmosphere taken away. You either place a regular ball 1m from the surface or a motherfucking neutron star.

Of course the surfaces will touch sooner with the neutron star.

The general formula just assumes one body has significantly lower mass than the other (i.e earth versus steel ball) so it tosses it out. Gravities of both bodies affect each other. The forces are added. There is no noticable difference between light small object and heavy small object, but heavy object will 'fall' faster.

[onepack No.3092448]

>>3092305
both same shape and volume. Read Ops conditions.

[Josef !!nUf2NflSAyw No.3092474]

Fun fact: the mass that appears in <span class="math">p=mv[/spoiler] is per se not the same mass that is in the Newtonian gravitational potential. Their equality was empirical only until general relativity came and actually required this to be the case; there's no theoretical need for the equality of gravitational and inertial mass.

[Josef !!nUf2NflSAyw No.3092478]

>>3092474 there's no theoretical need for the equality of gravitational and inertial mass.
... in Newtonian physics.
(Forgot adding that part, woops)