Transcript Science: Gravity

Gravity
By Asha Duhan
March 6,2011
What is Gravity?
Gravity is a Force Field surrounding the Earth. The Force
Field pulls anything that comes in orbit of the Earth towards
the Earth. Sometimes an Asteroid gets pulled into the Force
Field and makes huge craters in the Earths crust. Other times
the Asteroid is seen when it is really tiny (because it burned
up) with fire surrounding it which we call it a shooting star; it
should really be called a falling star.
Why is Gravity Important?
• If Earth did not have gravity, what do you
think would happen? Everything would be
floating around including you; perhaps we
would not even have an atmosphere. In
space there is no gravity or atmosphere.
Who Found out what Gravity was?
• Isaac Newton discovered gravity between 1684 and
1687. Newton was sitting under an apple tree and an
apple fell on his head. All of a sudden he started
wondering, “What made the apple come down on my
head instead of going up?” Newton named it
‘gravity’, after the Latin word gravitas, which means
weight.
What Causes Gravity?
• The cause of gravity is one of the biggest
mysteries of science. Physicists have
studied gravity for a while, but they still
don’t know what causes it.
Our Sun’s Gravity
• The Sun’s Force Field is a lot bigger than Earth’s Force
Field because the Sun is a lot bigger than the Earth.
• The Sun’s Force Field keeps our solar systems planets
in orbit.
Why does Gravity affect your
weight on other planets?
• Gravity affects your weight on other
planets because gravity’s strength can be
stronger or weaker on other planets. For
example, Mars has a weaker gravity than
Earth, and your weight on Mars is about
1/3 that on Earth. But on Jupiter your
weight is 2.64 times as much as your
weight on Earth.
Newton’s Laws of Gravity
• Newton spent many years discovering the law of gravity.
• According to this law everything pulls everything else to
itself with a force called gravity. How strong that force is
depends on how heavy the things are and how close
together.
• So even two apples pull toward each other. But, the
force is so small that you need a very careful experiment
to measure it. The reason that things fall toward the
ground is that the Earth we live on is so very heavy, and
we are so close to it.
• Newton's law of gravity not only explained how things fall
on earth, but why planets move around the sun and why
moons move around planets.
• http://www.dctech.com/eureka/short-stories/newton.php
How do Rockets get out of
Gravity’s pull and into Space?
• For a rocket to go into space, it has to point upwards. Its
engine needs to have enough power to beat the pull of
gravity, which means the engine must be very powerful
to launch the rocket.
Astronauts in the Shuttle in zero
Gravity Space
Resources
• http://www.qrg.northwestern.edu/projects/v
ss/docs/space-environment/1-what-isgravity.html
• http://wiki.answers.com/Q/When_did_newt
on_discover_the_law_gravity
• http://en.wikipedia.org/wiki/File:Solar_sys.j
pg
• http://wiki.answers.com/Q/How_does_a_ro
cket_go_into_space
Resources (continued)
• http://www.seismologik.com/journal/2010/7/29/sp
ace-stuff-nasa-layoffsthe-asteroid-that-coulddestroy-eart.html
• http://blogs.sundaymercury.net/weirdscience/201
0/05/newtons-tree-in-space.html
• http://wiki.answers.com/Q/How_does_gravity_aff
ect_weight_on_different_planets
• http://wiki.answers.com/Q/How_heavy_will_you_
be_on_Jupiter
• http://matchstic.com/blog/2008/08/months-inthe-making-new-matchstic-site-launch/
The End