Acceleration Due to Gravity: Facts & Qs

[Caesar_Rahil]

Is acceleration due to Gravity true?
I know it is a simple question, but I have other questions based on this.

 

[masudr]

Is acceleration due to Gravity true?

No.

(I have to make my message longer than 10 characters).

 

[HallsofIvy]

I would suggest to both of you that you climb onto the roof of your house (if you live in a high-rise apartment building so much the better!), step off the roof and see whether or not you are accelerated!

 

[moose]

There is a reason why we say the acceleration due to gravity on Earth is 9.8m/s^2

Unless I am completely missing the point...

 

[Aether]

I would suggest to both of you that you climb onto the roof of your house (if you live in a high-rise apartment building so much the better!), step off the roof and see whether or not you are accelerated!

Would this be a test of Newton's theory, Darwin's, or both?

 

[pervect]

Is philosphy real? :-)

 

[robphy]

Is acceleration due to Gravity true?

This is not a well-posed question.

I would suggest to both of you that you climb onto the roof of your house (if you live in a high-rise apartment building so much the better!), step off the roof and see whether or not you are accelerated!

In the spirit of this SR/GR forum... According to GR...

• after you step off your roof, you are traveling inertially... that is, you are in freefall, traveling along a spacetime geodesic... your 4-acceleration is zero.
• when you stand on your roof [or after you hit the ground], you are not traveling inertially, not traveling along a spacetime geodesic, and have a non-zero 4-acceleration.

 

[pmb_phy]

Is philosphy real? :-)

O-Man! Come on! I can't answer that! I'm still trying to figure out if I'm real.

Pete

 

[masudr]

I would suggest to both of you that you climb onto the roof of your house (if you live in a high-rise apartment building so much the better!), step off the roof and see whether or not you are accelerated!

I would suggest that you do that too, but carry drop several items alongside you. Notice that you and all the objects move alongside each other, regardless of rest mass and see that there is no acceleration, as robphy has pointed out.

 

[z-component]

Now that we have determined that there is acceleration due to gravity, what other questions do you have that you say are based on this fact?

 

[pmb_phy]

Is acceleration due to Gravity true?
I know it is a simple question, but I have other questions based on this.

It's far too difficult to respond to this question as stated since its unclear as to what is being asked.

I do, however, recommend that you avoid doing HallsofIvy's experiment.

I can't say more than robphy has already. He's a sharp man and beat me to what I'd have said.

Caesar - Can you refine your question more please? Thanks.

Pete

 

[Caesar_Rahil]

I never mentioned I have quesions that have to be asked in this forum only.


If a body is traveling with a speed of 99.99% the speed of light(Now don't tell me that's impossible). if it enter a strong gravitation force, say, the sun's wouldn't it be accelerated to a speed faster than light.

 

[pervect]

I never mentioned I have quesions that have to be asked in this forum only.
If a body is traveling with a speed of 99.99% the speed of light(Now don't tell me that's impossible). if it enter a strong gravitation force, say, the sun's wouldn't it be accelerated to a speed faster than light.

No, it won't. A simpler problem may illustrate why.

Suppose you have three rockets

A stands still
B moves at .9999c relative to A
---->
C moves at .9999c relative to B
---------->

What is the speed of C relative to A? The answer is given by the relativistic velocity addition formula

(.9999+.9999)/(1+.9999*.9999) = .999999995 times the speed of light.

You can imagine that rocket C is being accelerated either by gravity or a rocket engine (except that it will be hard to find a grav field strong enough to accelerate a rocket to .9999c).

Gravity makes things slightly harder to compute, but the basic principle is the same.