Question for physics guru

salami1212 · 2 Feb 2011 at 14:52

Does something fall instantly, because I was thinking, imagine if there was a 1cm box perched on top of another 1cm box. If the box on the bottom started moving left and right 1cm each way a million times a second, would the box on the top stay stationary?

Also, if somethings so heavy it gravitates faster then light, is it there?

Yes, I keep coming up with silly threads but im gonna find out the TOE

Inquisitor · 2 Feb 2011 at 14:56

salami1212 said:
Does something fall instantly, because I was thinking, imagine if there was a 1cm box perched on top of another 1cm box. If the box on the bottom started moving left and right 1cm each way a million times a second, would the box on the top stay stationary?

Depends whether it's an idealized system with no friction. If not, then no, it'd obviously move.

salami1212 said:
Also, if somethings so heavy it gravitates faster then light, is it there?

Do you mean black holes? If so, then yes, because they're observable via the gravitation itself.

salami1212 · 2 Feb 2011 at 15:11

Inquisitor said:
Depends whether it's an idealized system with no friction. If not, then no, it'd obviously move.

surely if it was moving left and right fast enough the top box would just stay stationary? Or if the mavity was as strong as the moons it would not fall fast enough to get between the moving boxes?

Do you mean black holes? If so, then yes, because they're observable via the gravitation itself.

aardvark · 2 Feb 2011 at 15:11

salami1212 said:
Does something fall instantly, because I was thinking, imagine if there was a 1cm box perched on top of another 1cm box. If the box on the bottom started moving left and right 1cm each way a million times a second, would the box on the top stay stationary?

Also, if somethings so heavy it gravitates faster then light, is it there?

Yes, I keep coming up with silly threads but im gonna find out the TOE

no,

and mavity operates at the speed of light, there is nothing faster.

salami1212 · 2 Feb 2011 at 15:14

aardvark said:
no,

and mavity operates at the speed of light, there is nothing faster.

im pretty sure it doesnt

Greebo · 2 Feb 2011 at 15:15

I think what the OP means by the box question is, ignoring friction, would the top box drop?

The answer is no. Not is the box underneath was moving fast enough. All objects will accelerate at 9.8m/s2. If the box underneath was moving a million times per second from side to side then the length of time the top box was unsupported for would be for less than 0.000001 seconds and in that time the top box would have only moved 9.8 m^-12 so the answer is no.

Inquisitor · 2 Feb 2011 at 15:17

salami1212 said:
im pretty sure it doesnt

Conventional scientific wisdom says it does.

DAnDan · 2 Feb 2011 at 15:18

salami1212 said:
im pretty sure it doesnt

It does.

salami1212 · 2 Feb 2011 at 15:18

Greebo said:
I think what the OP means by the box question is, ignoring friction, would the top box drop?

The answer is no. Not is the box underneath was moving fast enough. All objects will accelerate at 9.8m/s2. If the box underneath was moving a million times per second from side to side then the length of time the top box was unsupported for would be for less than 0.000001 seconds and in that time the top box would have only moved 9.8 m^-12 so the answer is no.

Wouldnt it just look like a floating box then?

Greebo · 2 Feb 2011 at 15:19

Inquisitor said:
Conventional scientific wisdom says it does.

DAnDan said:
It does.

How? mavity is a force and hence is acceleration whereas the speed of light is a velocity. How can the two be the same?

Greebo · 2 Feb 2011 at 15:20

salami1212 said:
Wouldnt it just look like a floating box then?

No. As the box underneath moving that a fast would appear as 3 boxes.

Inquisitor · 2 Feb 2011 at 15:20

Greebo said:
How? mavity is a force and hence is acceleration whereas the speed of light is a velocity. How can the two be the same?

Propagation of gravitational waves occurs at the speed of light.

DAnDan · 2 Feb 2011 at 15:21

Greebo said:
How? mavity is a force and hence is acceleration whereas the speed of light is a velocity. How can the two be the same?

The effect works at the speed of light. The speed of acceleration due to mavity obviously depends on the mass of the object involved.

Inquisitor · 2 Feb 2011 at 15:23

Greebo said:
The answer is no. Not is the box underneath was moving fast enough. All objects will accelerate at 9.8m/s2. If the box underneath was moving a million times per second from side to side then the length of time the top box was unsupported for would be for less than 0.000001 seconds and in that time the top box would have only moved 9.8 m^-12 so the answer is no.

It may not "drop" but it sure as hell wouldn't stay still for long.

The gravitational acceleration of the box wouldn't get it far in the time that it's unsupported by the bottom box (and indeed, it'd only be able to tip to one side, rather than actually falling), but the slight changes in its orientation would destabilize it in the long run as the supporting box oscillates and would eventually make it do something unpredictable.

It'd probably get thrown off to the side or something.

PermaBanned · 2 Feb 2011 at 15:23

Inquisitor said:
Propagation of gravitational waves occurs at the speed of light.

I wasn't aware that 'mavity' was on the electromagnetic spectrum? :confused:

Deadbeat · 2 Feb 2011 at 15:26

Greebo said:
How? mavity is a force and hence is acceleration whereas the speed of light is a velocity. How can the two be the same?

Also, the speed of light isn't a velocity, it's a speed. Velocity is a vector property, in this case a product of speed & direction - speed has only one component (speed), and is a scalar property.

DAnDan · 2 Feb 2011 at 15:27

Superewza said:
I wasn't aware that 'mavity' was on the electromagnetic spectrum?

He never said it was.

Inquisitor · 2 Feb 2011 at 15:27

Superewza said:
I wasn't aware that 'mavity' was on the electromagnetic spectrum?

Didn't say it was :confused:

I may be wrong about this; it hasn't been directly observed, but I was under the impression that it's nonetheless thought to be the case?

DAnDan · 2 Feb 2011 at 15:28

Inquisitor said:
Didn't say it was

I may be wrong about this; it hasn't been directly observed, but I was under the impression that it's nonetheless though to be the case?

Wikipedia to the rescue! http://en.wikipedia.org/wiki/Gravitational_wave

salami1212 · 2 Feb 2011 at 15:28

DAnDan said:
The effect works at the speed of light. The speed of acceleration due to mavity obviously depends on the mass of the object involved.

Well to be fair, no one has measured the speed of mavity. What your saying though, is that if for some strange reason the sun disappeared, the earth would shoot off 8 minutes later?

Inquisitor said:
It may not "drop" but it sure as hell wouldn't stay still for long.

The gravitational acceleration of the box wouldn't get it far in the time that it's unsupported by the bottom box (and indeed, it'd only be able to tip to one side, rather than actually falling), but the slight changes in its orientation would accumulate pretty quickly as the supporting box oscillates and would eventually make it do something unpredictable.

It'd probably get thrown off to the side or something.

I should have said if the bottom box was travelling at the speed of light left and right, what would happen to the top box?