A historical question

1. Sep 8, 2004

somy

a historical question!!!

I have a question about galileo's experiment on top of the pizza !!!
(maybe it seems a bit silly!!!)
Can anyone tell me how did he say from this experiment that:
mass of gravity and inertia are identical???
Thanks a lot.
Somy

2. Sep 8, 2004

humanino

He simply made several balls of several weights rolling down on a inclined plane, and noticed all the mass had the same acceleration.

It seems easy today. The greatest achivement was to find an accurate mean to measure time.

3. Sep 8, 2004

Staff: Mentor

From the way you phrased that ("mass of gravity") sounds like maybe you misunderstand the difference between weight and mass and inertia. Inertia is resistance to motion due to mass, weight is gravitational attraction due to mass. For rolling balls down an incline (or dropping them off the tower of Piza, which probably didn't happen), since weight is proportional to mass and inertia is proportional to mass, the change in mass cancels out and thus all objects fall (accelerate due to G) at the same rate.

4. Sep 8, 2004

humanino

:rofl: :rofl: :rofl:
I could not figure out what pizza came here !
You gave me a good laugh. It is the city Pisa ! We dumb french call it "pise" (prononce like pizza, without the a)

thanks for the clarification russ_watters, which has been useful to me too !

5. Sep 8, 2004

Staff: Mentor

D'oh. I knew it wasn't "pizza" - but that only got me halfway there. In English, it sounds almost exactly like pizza though.

6. Sep 9, 2004

joyful55

I still can't figure out what has any of this got to do with pizza?

7. Sep 9, 2004

Staff: Mentor

There is a legend, probably false, that Galileo dropped objects off the leaning tower of Pisa to test his theory of gravity.

8. Sep 9, 2004

somy

Dear guys:
I haven't got my answer yet.
Thanks a lot.
somy

9. Sep 9, 2004

humanino

10. Sep 9, 2004

humanino

I agree. Pizza have nothing to do with the city Pisa. Pizza were invented in Milano way before Galileo in history :rofl: :rofl:

Damn : pizza fans, check this

11. Sep 9, 2004

somy

well, I didn't get the russ watters' answer.
(I'm a bit silly!!!)

12. Sep 9, 2004

LURCH

By dropping (or rolling) things, he put two opposing forces against one another; gravity would attempt to accelerate the objects, while inertia resisted that acceleration. By showing that objects of different mass fall at the same rate, he showed that, as mass increases, resistance to acceleration (inertia) increases by exactly the same amount as does the force of acceleration toward the ground (gravitation).

13. Sep 9, 2004

Staff: Mentor

If you didn't get Lurch's answer (which is similar to mine but phrased differently), could you rephrase your question or be more specific about what part you don't understand?