Download Slide 1

U3 MOTION:
FORCES IN THE UNIVERSE
What is a force?
A force is a push or a pull
Forces can:
Start or Stop objects moving
Change direction or shape of an object
Increase or decrease the speed of an object
Four Fundamental Forces
1.
2.
3.
4.
1. Strong Nuclear Force
• An interaction between particles that hold
the atomic nuclei together. It is mostly
attractive but can be repulsive in some
situations.
• It is the strongest force
• Short range (over 10-13 centimeters)
2. Weak Nuclear Force
• An interaction between particles responsible
for radioactive decay.
• It is the 2nd weakest force
• Short Range
3. Electromagnetic
Force
• An interaction between
particles that causes
electric and magnetic effects.
• It can be attractive or repulsive.
• Acts only between pieces of matter carrying
electrical charge.
• Responsible for the emission and absorption
of photons (Electromagnetic Radiation).
• The phenomena of electricity and magnetism
are consequences of this force.
4. Gravity
• An attractive interaction between pieces of
matter resulting from their mass and their
distance.
• Weakest force but long range (can stretch
into infinite amount of space)
• We would not exist without it
What do you already know
about gravity?
• Write down any
knowledge you
have on gravity.
Objects affected by Earth’s gravity
Gravity is responsible for:
Forming and maintaining (orbits)
our Solar System
Orbits of natural
and
artificial satellites
Interactions
between objects
• The Sun has a vast effect on the motion of
planets in our solar system. Even though
planets are smaller than the Sun the
planets still exert a gravitational pull on the
Sun.
• We can detect new planets in other solar
systems due to wobbles in orbits of
identified planets.
Star’s Fusion – the core of the
star pulls in matter
Accretion – collection of matter
(formed our Earth)
Earth’s Convection Currents
Convection currents move matter toward
core due to gravity and decreasing density
Plate tectonics or movement of Earth’s
plates is due to convection currents.
Earth’s Tides
Tides are caused by the sun and moons gravitational pull, When the sun and
moon are aligned, there are exceptionally strong gravitational forces, causing very
high and very low tides which are called spring tides, though they have nothing to
do with the season. When the sun and moon are not aligned, the gravitational
forces cancel each other out, and the tides are not as dramatically high and low.
These are called neap tides
Bending of
Light
The Water Cycle
Interactions in the Human Body
As we age gravity
affects the human body
What problems do the
astronauts have on their
body while in space and
far from Earth’s gravity ?
•
•
•
•
Muscle loss/decay
Bones become brittle
Blood centers near heart
Radiation exposure
Blood Flow
Who was responsible for discovering the
relationship between gravity and orbital paths?
Sir Issac Newton
• Apple
• Motion Laws
• Inertia
Newton’s
Universal Law of Gravitation Part I
Newton’s
Universal Law of Gravitation Part II
Newton’s Law Recap
The greater your mass
the stronger…
The closer your distance
the stronger…
Bibliography
http://mediatheek.thinkquest.nl/~ll125/images/convect.jpgl
http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html#c3
http://library.thinkquest.org/C003763/images/adapt/spaceman.jpg
http://quest.nasa.gov/space/teachers/rockets/images/satellite_orbit.gif
http://www.astrosurf.com/cidadao/moon_99_02_23_south.jpg
http://z.about.com/d/space/1/0/Y/Q/sun_tour.jpg
http://ifpower.apogee.net/kids/graphics/lnh2.jpg
http://library.thinkquest.org/27585/frameset_intro.htm
http://library.thinkquest.org/27585/frameset_intro.htm