Presentation1

causes of motions

What causes motion?

Imagine a world without motion. There would be no wind and rain, no night and day, no cars and airplanes, no birds and fish, no animals and plants- no life

After all everything on earth is made up of tiny, randomly moving particles called molecules. Earth itself is like a giant spaceship circling the Sun, spinning on its axis as it moves. All creatures on Earth live in a continuous whirl of motion.

Causes of motion

Change in position of a body relative to another body or with respect to a frame of reference or coordinate system is the cause of motion. Force. Field.

If anything is acting on a partilce, it will keep moving along a straight line, with constant velocity (in all the inertial reference frames). In this sense, nothing causes the motion. A change in this kind of motion, that is, an acceleration or a curve in the trajectory, is caused by a force, according to the Newton equation

F = dp/dt. "Nowadays" we prefer to avoid the concept of force F, using

instead the idea of field, which is independet from the particle and from its parameters (mass, charge, ... ): you can say that the field permeate the space, whether the particle is there or not.

12.1 EARLY STUDIES ON CAUSES OF MOTION

AristotleOver 2000 years ago, a Greek philosopher named Aristotle(384-322 BC) He included that objects needed a continuous push or pull to keep moving. If the push and or pull where removed, the object would stop moving.

ARISTOTLE WHO FIRST TO ANALYZE AND OBSERVE THE CAUSES OF MOTION. HE OBSERVE THAT WHEN AN OBJECT WAS

PUSH OR PULL THE OBJECT WILL CONTINUE TO MOVED AND WHEN THE AN OBJECT WAS

NOT PUSH OR PULL THE OBJECTWILL REMAIN AT REST. THIS OBSERVATION

WAS CONSIDER BUT WHEN GALILEO EXPERIMENTED THAT WHEN AN OBJECT

WAS AT REST IT WILL REMAIN AT REST AND WHEN AN OBJECT WAS MOVED IT WILL CONTINUE MOVED FROM ONE PLACE

TO ANOTHER.

aristotle

•Born: 384 B.C. 

•Birthplace: Stagira, Macedonia (now Greece) 

•Died: 322 B.C. 

•Best Known As: The author of Ethics

GALILEO GALILEE

Galileo Galilei was born in Pisa, Italy on February 15, 1564. He was the oldest of seven children. His father was a musician and wool trader, who wanted his son to study medicine as there was more money in medicine. At age eleven, Galileo was sent off to study in a Jesuit monastery.

Galileo was taught Aristotelian physics at the university of Pisa. But he quickly began questioning this approach. Where Aristotle had taken a qualitative and verbal approach, Galileo developed a quantitative and mathematical approach. Where the Aristotelians argued that heavier bodies fell faster than lighter ones in the same medium, Galileo, early in his career, came to believe that the difference in speed depended on the densities of the bodies. Where Aristotelians maintained that in the absence of the resisting force of a medium a body would travel infinitely fast and that a vacuum was therefore impossible, Galileo eventually came to believe that in a vacuum all bodies would fall with the same speed, and that this speed was proportional to the time of fall.

ASIDE FROM HIS NUMEROUS INVENTIONS, GALILEO ALSO LAID DOWN THE FIRST ACCURATE LAWS OF MOTION FOR MASSES. GALILEO REALIZED THAT ALL BODIES ACCELERATE AT THE SAME RATE REGARDLESS OF THEIR SIZE OR MASS. EVERYDAY EXPERIENCE TELLS YOU DIFFERENTLY BECAUSE A FEATHER FALLS SLOWER THAN A CANNONBALL. GALILEO'S GENIUS LAY IN SPOTTING THAT THE DIFFERENCES THAT OCCUR IN THE EVERYDAY WORLD ARE IN INCIDENTAL COMPLICATION (IN THIS CASE, AIR FRICTION) AND ARE IRRELEVANT TO THE REAL UNDERLYING PROPERTIES (THAT IS, GRAVITY). HE WAS ABLE TO ABSTRACT FROM THE COMPLEXITY OF REAL-LIFE SITUATIONS THE SIMPLICITY OF AN IDEALIZED LAW OF GRAVITY.

12.1 Galileo's concept of motion illustrated

Upward slope decreasing speed

Downward slope increasing

speed

a

Final position

Initial position

b

c

final positionInitial

position

Initial position Where is

the final position?

d

Galileo galilee

Born15 February 1564Pisa, Duchy of Florence, ItalyDied8 January 1642 (aged 77)Arcetri, Grand Duchy of Tuscany, ItalyResidenceGrand Duchy of Tuscany, ItalyNationalityItalian (Tuscan)FieldsAstronomy, physics and mathematicsInstitutions

Click icon to add picture

Thank You For Watching …