Nother physics question

**LBD** · 5th September 2009, 21:03

So the aim, was pose a straight forward logic thinking gravity question…

Gravity is an attractive force one mass exerts on another mass.

We all know that the further from the surface of the earth we move the portable mass, the less the scales will read until we go beyond any of the earths discernable gravitational force.

For normal thinking, the force of gravity is calculated from the center of the mass, but what happens when you lower one mass inside the other? The further toward the center of the large mass (Earth) the more of the earth's mass is above the 10kg . This mass above, also exerts a gravitational pull on the 10 kg, countering the pull toward the centre of the earths mass….The deeper the mine the less weight detected by the scales.

Correct answer was B

Blings to those on the ball….

Jantar was the first….His turn…..

**Ronin** · 5th September 2009, 21:24

You are all missing the point. In todays society we should be asking:

How does the water feel about being the centre of an experiment.
Did the water receive enough hugs as a rain drop
Are there any possible treaty claims that could arise from this experiment
Is the water speeding when you take it down the shaft?

**Big Dave** · 5th September 2009, 22:06

Originally Posted by Ronin

Is the water speeding when you take it down the shaft?

Beavis voice: he said 'shaft'. hsssshsss

**MisterD** · 6th September 2009, 08:39

Originally Posted by LBD

Correct answer was B

Blings to those on the ball….

Jantar was the first….His turn…..

My further reading indicates that in reality because of the density changes within the Earth, gravity increases and peaks at the mantle/core boundary...

**Big Dave** · 6th September 2009, 10:29

Originally Posted by MisterD

My further reading indicates that in reality because of the density changes within the Earth, gravity increases and peaks at the mantle/core boundary...

I just dug a hole down to it in the back yard and can verify that.

**Usarka** · 6th September 2009, 11:59

is this busted yet?

**bogan** · 6th September 2009, 12:16

Originally Posted by LBD

For normal thinking, the force of gravity is calculated from the center of the mass, but what happens when you lower one mass inside the other? The further toward the center of the large mass (Earth) the more of the earth's mass is above the 10kg . This mass above, also exerts a gravitational pull on the 10 kg, countering the pull toward the centre of the earths mass….The deeper the mine the less weight detected by the scales.

Correct answer was B

right answer, wrong working imo

Originally Posted by MisterD

My further reading indicates that in reality because of the density changes within the Earth, gravity increases and peaks at the mantle/core boundary...

agreed, as the mass is moved down the mineshaft, it has a larger gravitational force, but.... the air becomes denser, so the weight of the displaced mass of air greatly increases, making the water bouyant, and lighter than it was at the earth surface.