Download presentation

Presentation is loading. Please wait.

Published byKennedy Glidden Modified over 2 years ago

2
Chapter 9 & 10 Gravity

3
Pythagoras (550 BC) n Claimed that natural phenomena could be described by mathematics

4
Aristotle (350 BC) n Asserted that the universe is governed by physical laws

5
n The ancient Greeks believed that the earth was at the center of a revolving sphere with stars on it.

6
n The Geocentric Model implies Earth-Centered Universe.

8
Copernicus(1500's) n Developed a mathematical model for a Sun-centered solar system

10
Tycho Brahe (1500's) n Made precise measurements of the positions of the planets

11
Kepler(1600's) n Described the shape of planetary orbits as well as their orbital speeds

13
Kepler’s First Law n The orbit of a planet about the Sun is an ellipse with the Sun at one focus.

14
Kepler’s Second Law n A line joining a planet and the Sun sweeps out equal areas in equal intervals of time.

15
Kepler’s Third Law n The square of a planet's orbital period is proportional to the cube of the length of its orbit's semimajor axis. n Or simply… T 2 = R 3 if T is measured in years and R is measured in astronomical units.

16
An Astronomical Unit... n …is the average distance of the Earth from the Sun. n 1 AU = 93,000,000 miles = 8.3 lightminutes

17
Kepler’s Laws n These are three laws of physics that relate to planetary orbits. n These were empirical laws. n Kepler could not explain them.

18
Kepler’s Laws...Simply (See page 192.) n Law 1: Elliptical orbits… n Law 2: Equal areas in equal times… n Law 3: T 2 = R 3

19
Newton’s Law of Universal Gravitation n From Kepler's 3rd Law, Newton deduced inverse square law of attraction. G=6.67 10-11 N m 2 /kg 2 G=6.67 10-11 N m 2 /kg 2

20
Gravity Questions n Did the Moon exert a gravitational force on the Apollo astronauts? n What kind of objects can exert a gravitational force on other objects? n The constant G is a rather small number. What kind of objects can exert strong gravitational forces?

21
Gravity Questions n If the distance between two objects in space is doubled, then what happens to the gravitational force between them? n What is the distance is tripled? n …is quadrupled? n What if the mass of one of the object is doubled? n …tripled? n …quadrupled?

22
Weight and Weightlessness n Weight »the force due to gravity on an object »Weight = Mass Acceleration of Gravity »W = m g n Weightlessness - a conditions wherein gravitational pull appears to be lacking –Examples: »Astronauts »Falling in an Elevator »Skydiving »Underwater

23
Ocean Tides n The Moon is primarily responsible for ocean tides on Earth. n The Sun contributes to tides also. n What are spring tides and neap tides?

24
Sun Earth New MoonFull Moon Spring Tides

25
Sun Earth First Quarter Last Quarter Neap Tides

26
End of Section…

27
Einstein’s Theory of Gravitation n Einstein perceived a gravitational field as a geometrical warping of 4-D space and time.

28
BLACK HOLES 4Let’s observe a star that is shrinking but whose mass is remaining the same. 4What happens to the force acting on an indestructible mass at the surface of the star? SFA

29
R2R2 F R2R2 F R2R2 F R2R2 F R R R R Remember that the force between the two masses is given by

30
4If a massive star shrinks enough so that the escape velocity is equal to or greater than the speed of light, then it has become a black hole. 4Light cannot escape from a black hole. BLACK HOLES

31
Near a Black Hole

Similar presentations

OK

Universal Gravitation. 2Physics 1100 – Spring 2012 Chapter 9 - Gravity Universal Law of GravityUniversal Law of Gravity Universal Gravitational Constant,

Universal Gravitation. 2Physics 1100 – Spring 2012 Chapter 9 - Gravity Universal Law of GravityUniversal Law of Gravity Universal Gravitational Constant,

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on tamper resistant electrical outlets Jit ppt on manufacturing processes Ppt on solar energy in hindi Ppt on solid dielectrics definition Free ppt on network topology Download ppt on national festivals of india Ppt on automobile related topics about work Ppt on layer 3 switching wiki Ppt on complex numbers class 11th notes Ppt on p&g products brands tide