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Re: Gravity......
Posted by 'ChrisAdams' on 02 Jan 2011 @ 22:01

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ChrisAdamsJoined: August 2001
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My understanding of physics does not extend as far as where gravity comes from or what causes it. I am merely answering the initial question by Newshound - is gravity a force or an acceleration. Answer - it is an acceleration.

To prove it: Try dropping two different objects of a similar shape (for similar aerodynamic properties) but a different mass from the same height.

For an example use an average hammer (heavier object) and a screwdriver (lighter object).

Providing both the hammer and the screwdriver are released at the same time then they will also hit the floor at the same time (give or take a fraction of a second due to different aerodynamic properties). Try it, its true!

The two objects of different mass accelerate (due to gravitional acceleration) towards the ground at exactly the same rate.

Taking the equation F = ma

If gravity was a force (and a constant) then (I assume we can agree that we can take mass as a constant!) then the acceleration would be the variable and reduce as the mass increased (re-arranging the equation to a = F/m, as the mass increases, the acceleration reduces). Thus if gravity was a force then the lighter object should hit the ground first! This simply is not the case!

No matter the mass (if you take out aerodynamic properties) objects will accelerate towards the earth at the same rate.

The difference between the heavier and lighter objects is the force that they excert due to gravitational acceleration. Taking the above example, the hammer will hit the ground with a higher force because it has a higher mass.

Force due to gravitational acceleration differs between objects. Hence I more than likely see a higher figure than you when I jump on the scales!

If gravity was a force then we would all weigh the same, but if we both jumped in the air, I would take longer to return to earth... because I am heavier....!

Chris

Message Thread:

Gravity...... by 'Newshound' (29 Dec 2010 @ 20:03)

Re: Gravity...... by 'HarryC' (29 Dec 2010 @ 20:59)

Re: Gravity...... by 'John' (29 Dec 2010 @ 23:36)

Re: Gravity...... by 'Newshound' (29 Dec 2010 @ 23:51)

Re: Gravity...... by 'alanrr' (30 Dec 2010 @ 11:23)

Re: Gravity...... by 'rich84' (30 Dec 2010 @ 15:10)

Re: Gravity...... by 'Newshound' (30 Dec 2010 @ 16:01)

Re: Gravity...... by 'Tmoon' (01 Jan 2011 @ 15:16)

Re: Gravity...... by 'colingray' (02 Jan 2011 @ 9:41)

Re: Gravity...... by 'ChrisAdams' (02 Jan 2011 @ 10:55)

Re: Gravity...... by 'colingray' (02 Jan 2011 @ 19:24)

Re: Gravity...... by 'ChrisAdams' << You are here!

Re: Gravity...... by 'colingray' (03 Jan 2011 @ 1:39)

Re: Gravity...... by 'glittttt' (03 Jan 2011 @ 12:32)

Re: Gravity...... by 'colingray' (03 Jan 2011 @ 12:47)

Re: Gravity...... Is a Force by 'davidmc' (03 Jan 2011 @ 13:19)

Re: Gravity...... Is an acceleration! by 'ChrisAdams' (03 Jan 2011 @ 14:45)

Re: Gravity...... Is an acceleration! by 'colingray' (03 Jan 2011 @ 15:34)

Re: Gravity...... Is an acceleration! by 'colingray' (03 Jan 2011 @ 15:37)

Re: Gravity...... Is a force! by 'davidmc' (03 Jan 2011 @ 16:10)

Re: Gravity...... Is a force! by 'colingray' (03 Jan 2011 @ 17:16)

Re: Gravity...... Is a force! by 'ChrisAdams' (03 Jan 2011 @ 18:47)

Re: Gravity...... Is a force! by 'davidmc' (03 Jan 2011 @ 19:31)

Re: Gravity...... Is a force! by 'ChrisAdams' (03 Jan 2011 @ 20:32)

Re: Gravity...... Is a force! by 'SimonS' (08 Jan 2011 @ 16:20)

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