Galileo GalileiGalileo Galilei

Early YearsEarly Years

Born 15 Feb. 1564 in PisaBorn 15 Feb. 1564 in Pisa Educated in Camaldolese MonasteryEducated in Camaldolese Monastery Father wanted him to be a medical Father wanted him to be a medical

doctordoctor Interested in mathematicsInterested in mathematics

Observed swinging lamps in Cathedral of Pisa and found period to be independent of the amplitude – idea for a pendulum clock

Used inclined planes to prove that bodies do not fall with velocities proportionate to their weight but proportionate to time.

Found that projectiles follow a parabolic pathFound that projectiles follow a parabolic path

Galileo’s Telescope• Improved Dutch spyglass to achieve 8-9X magnification

• Observed mountains on the moon, the Milky Way composed of tiny stars, and sunspots

Accurately measured the period for four of Accurately measured the period for four of Jupiter’s moonsJupiter’s moons

Saw that Venus showed phases like the moon Saw that Venus showed phases like the moon did and must therefore orbit the Sun rather did and must therefore orbit the Sun rather than the Earththan the Earth

COPERNICAN THEORY

• I hold that the Sun is located at the centre of the revolutions of the heavenly orbs and does not change place, and that the Earth rotates on itself and moves around it. Moreover ... I confirm this view not only by refuting Ptolemy's and Aristotle's arguments, but also by producing many for the other side, especially some pertaining to physical effects whose causes perhaps cannot be determined in any other way, and other astronomical discoveries; these discoveries clearly confute the Ptolemaic system, and they agree admirably with this other position and confirm it.

• In February 1632 Galileo published Dialogue Concerning the Two Chief Systems of the World - Ptolemaic and Copernican . ,

Catholic ChurchCatholic Church Galileo found guilty of Galileo found guilty of

breaching the Inquisition of breaching the Inquisition of 1616 and sentenced to lifelong 1616 and sentenced to lifelong imprisonmentimprisonment

Allowed house arrest rather Allowed house arrest rather than imprisonmentthan imprisonment

On 31 October 1992 Pope John Paul II spoke On 31 October 1992 Pope John Paul II spoke on behalf of the Catholic Church admitting on behalf of the Catholic Church admitting the theological advisors had made errors, the theological advisors had made errors, but did not admit that the Church was but did not admit that the Church was wrong to convict Galileo on a charge of wrong to convict Galileo on a charge of heresy because they were acting according heresy because they were acting according to the best of their knowledgeto the best of their knowledge

GALILEO AND SCIENTIFIC METHOD

• 1602-Pendulum experiments.• 1604- Inclined plane experiments of natural

acceleration.• 1607-Systematic manipulation of shapes and

weights of wax balls to study flotation.• Investigation of projectile motion. Discovery of

parabolic character of projectile motion.• 1609 Observations of Jupiter Moons

Three Experiments 1. The Pendulum: Used to demonstrate the law of inertia and that heavy and

light bodies fall at the same rate. Galileo also discovered the mathematical laws governing the length of the string, the period of the motion, and the amplitude of the swing.

2. The Inclined Plane and the Rate of Acceleration: Galileo used the inclined plane to slow the motion of falling objects enough to accurately measure how their speed increased.

3. Projectile Motion: Galileo also used the inclined plane to control the speeds and heights of projectiles in order to discover the mathematical properties of their paths.

"...repeat many times the fall through a small height in such away that I might accumulate all those intervals of time that elapse between the arrival of the heavy and light bodies respectively at their common terminus, so that this sum makes an interval of time which is not only observable, but easily observable."  

"...two balls, one of lead and one of cork, the former more than a hundred times heavier than the latter, and suspended them by means of two equal fine threads, each four or five cubits long. "This free vibration repeated a hundred times showed clearly that the heavy body maintained so nearly the period of the light body that neither in a hundred swings nor even in a thousand will the former anticipate the latter by as much as a single moment, so perfectly do they keep step."         Galileo  

Inclined PlaneInclined Plane"...in such a plane, just as well as in a vertical plane, one "...in such a plane, just as well as in a vertical plane, one

may discover how bodies of different weight behave..." may discover how bodies of different weight behave..."  Galileo Galileo

Inclined PlaneInclined Plane"...in such a plane, just as well as in a vertical plane, one may discover how bodies of different weight behave..."  "...in such a plane, just as well as in a vertical plane, one may discover how bodies of different weight behave..." 

GalileoGalileo

Total distance traveled is proportional to the square of time.

3. Projectile Motion3. Projectile Motion

Projectile MotionProjectile Motion

The object goes into free fall as it The object goes into free fall as it exits the inclined planeexits the inclined plane

Vertical motion can be separated Vertical motion can be separated from the horizontal motionfrom the horizontal motion