This presentation describes what is gravity, microgravity and artificial gravity. It also showcases the Gravity Probe B.

1. "Relativity teaches us the connection between the different
descriptions of one and the same reality."
-A. Einstein
Gravity
By Gladys Palacio Velez

2. What is Gravity?
Answer: Nobody truly knows what gravity is.
But thanks to scientists throughout history we know how gravity behaves
and it’s effects.
 In 1687 Sir Isaac Newton proposes his law of gravitation
in which it states that every body in the universe attracts
all other bodies with a force that is directly proportional
with their masses and inversely proportional with its
Sir Isaac Newton
distance.

3. Microgravity
 Is there gravity in space? YES!
 Some people are confused that their isn’t any gravity in
space because we see astronauts doing flips in mid-air
and their hair standing up, meanwhile, in Earth everything
sticks to the floor.
 Microgravity is one-millionth (1 x 10^-6)
of Earth’s gravity.
 Microgravity isn’t all about being able to
cool tricks in air but it also brings negative
effects to the human body in:
• Musculoskeletal
• Neural system
• Cardiovascular

4. Creating Microgravity
 A Microgravity Environment is obtained when any object is found
in the state of free fall.
 Free fall = “the (one-dimensional) motion of any object under the
influence of gravity only.”
 Examples of microgravity environments:
Flying Parabolic Arcs
Neutral Buoyancy Laboratories
 These examples given are used to train astronauts
to learn how to work in the microgravity
environment in space to perform the missions. All objects free fall at the
same rate of acceleration
regardless of their mass.

5. Artificial Gravity
 Artificial gravity is the varying of apparent gravity via artificial
means, particularly in space, but also on the Earth.
 Methods for generating artificial gravity:
• Rotation
• Linear Acceleration
• Mass
• Magnetism
• Gravity Generator
• Buoyancy
 The importance of artificial gravity in
space is protect the astronauts from the This device would spin at a
harmful effects of being subjected to speed that would simulate
microgravity for prolonged periods of time. the gravitational pull of
Earth.

6. Gravity Probe B
 Launched on April 20, 2004
GP-B is a mission to experiment that tests
Einstein's 1916 general theory of relativity.
The GP-B used four spherical gyroscopes,
a telescope, and a star to measure two effects from Einstein Theories:
• geodetic effect = the amount by which the Earth warps the local spacetime in
which it resides.
• The frame-dragging effect = the amount by which the rotating Earth drags its
local spacetime around with it.

7. Einstein Theories are correct!
 Einstein’s General Theory of Relativity states that space and time
are relative entities, interwoven fabric whose curvature is gravity.
 “Every one of the planets and stars and galaxies causes a
depression that can attract or deflect passing smaller
objects.” - Joanne Baker, 50 Physics Ideas
 After analyzing the data obtained by the GP-B for
5 years, scientists from NASA confirmed this theory.

8. Gravity Assist
 It’s the use of the relative movement and gravity of a planet or other celestial
body to alter the path and speed of a spacecraft, typically in order to
save propellant, time, and expense.
 Gravity assistance can be used to accelerate,
decelerate and/or re-direct the path of a spacecraft.
 Before every space mission a trajectory needs to
be designed for when sending a spacecraft.
The trajectories that enabled NASA's twin Voyager spacecraft to tour the four
gas giant planets and achieve velocity to escape our solar system had to use
gravity assist.

9. Importance of Gravity in our Daily Life
 Without gravity we couldn’t live in the world we know because gravity is
everywhere!
 Gravity is what keeps are bones functioning to be capable of giving support to
our weight. It keeps satellites orbiting Earth so we can have communication.
 By understanding how gravity behaves we’ve been able to expand our
knowledge in the universe and in our own planet and develop ground breaking
technology. And soon enough we’ll reach Mars and asteroids.

10. Bibliography
 Some Guy. (2006). Albert Einstein Quotes. Retrieved December 26, 2011, from The Random Factor:
http://www.some-guy.com/quotes/einstein.html
Than, K. (2011, May 5). Einstein Theories Confirmed by NASA Gravity Probe. National Geographic
Daily News.
(2007). General Relativity. In Baker, 50 Physics Ideas You Really Need to Know (pp. 164-167). Quercus.
What is Microgravity? (2009). Retrieved December 28, 2011, from NASA:
http://www.nasa.gov/centers/glenn/shuttlestation/station/microgex.html
The Physics Classroom. (1996-2011). Retrieved December 28, 2011, from Newton's Second Law of
Motion: http:/www.physicsclassroom.com/class/newtlaws/u2l3e.cfm
Retrieved December 28, 2011, from Gravity Probe B Testing Einstein's Universe:
http://einstein.stanford.edu/index.html
Artificial Gravity. (n.d.). Retrieved December 29, 2011, from Wikipedia:
http://en.wikipedia.org/wiki/Artificial_gravity
Creating Artificial Gravity in Space. (2001 - 2011). Retrieved December 29, 2011, from Softpedia:
http://news.softpedia.com/news/Creating-Artificial-Gravity-in-Space-141880.shtml
Gravity Assit. (n.d.). Retrieved December 29, 2011, from Wikipedia:
http://en.wikipedia.org/wiki/Gravity_assist