Newton
Newton (1642 - 1727)
Born 1642 - the year Galileo died
Graduated from Cambridge 1665
Because of the plague he returned to Woolsthorpe (1665 - 1667)
During these two year he developed:
- the binomial theorem
- calculus
- decomposition of white light into colours
- began studying motion (mechanics)
- formulated his ideas about gravitation
- Returned to Cambridge as a lecturer in 1667
Most important published work : Principia Mathematica
- Noted mathematician Isaac Barrow resigned his chair of mathematics
so that Newton could freely follow his studies
- Used rigorous logic and axiomatic style (Euclid)
- Newton’s first publications (optics) were not well received
by the British scientific community
- Newton studied alchemy, theology, and Biblical prophecy
and did not publish again for 20 years.
- From a number of basic definitions three laws of motion and
the law of universal gravitation were proposed
- By deduction Newton showed that the observed motions
of objects were consequences of his definitions and laws of motion
- Described as :jealous, egotistical, complex, and troubled.
Absent-minded, confirmed bachelor
- Had heated rivalries with Flamsteed and Leibnitz
Newton’s Ideas:
- Quantity of matter (mass)
- Quantity of motion ( mass X velocity) (momentum)
- Inertia
- Impressed force
- Fundamental quantities mass, time, and length, i.e. dimensions
(Required to be measurable independent of
the state of mind of the observer)
Three Laws of Motion
1. In the absence of a net external force, an object will continue
in a state of uniform motion (including rest)
in a straight line (Law of Inertia)
2. The time rate of change of motion (momentum)
of an object is directly proportional to the magnitude and
direction of the impressed force F = ma (Law of Acceleration)
3. For every action there is an equal and opposite reaction
(Law of Action and Reaction)
Universal Law of Gravitation
Every material particle in the universe attracts every other material
particle with a force that is proportional to the product of the masses
of the two particles and inversely proportional to the square of the
distance between their centres. The force of attraction is directed
along a line joining their centres.
F = G m1m2
r2
Conservation Laws
- conservation of mass
- conservation of momentum