U3 MOTION: FORCES IN THE UNIVERSE Gravity is the force of attraction We would not exist without it Accretion, condensation, planets, sun, moon, stars heated, convection currents, human body

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. SForce – strongest but closest between Neutrons & protons in atoms Weak- Helps for nuclear fusion of H in sun and radioactive decay EM – keeps atom together or molecules neg and pos chgs Electromagnetism is responsible for interactions between charged particles that occur because of their charge, and for the emission and absorption of photons (electromagnetic radiation). The phenomena of electricity and magnetism are consequences of this force, Gravity – weakest but can stretch into infinite amount of space 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 Satellites in LOE must travel really fast so that the pull of gravity doesn’t tug them back into the atmosphere Moon revolves around Earth Sun is actually affected a little and wobbles due to planets nearby actually many planets wobble

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 Muscles- loss and decay, Bones-brittle lose vitamins and minerals, Blood slows still some gravity Artificial gravity for Russian 429 days in space

Blood Flow

Who was responsible for discovering the relationship between gravity and orbital paths? Gravity keeps planets in orbit around the sun

Sir Issac Newton Apple Motion Laws Inertia A=change in velocity or speed or direction AccelerationThen, the orbit of the Moon about the Earth could be a consequence of the gravitational force, because the acceleration due to gravity could change the velocity of the Moon in just such a way that it followed an orbit around the earth. The tendency for Objects to resist change in motion

Newton’s Universal Law of Gravitation Part I Newton came to the conclusion that any two objects in the Universe exert gravitational attraction on each other The more mass you have the more gravity

Newton’s Universal Law of Gravitation Part II

Newton’s Law Recap The greater your mass the stronger… The closer your distance the stronger… To determine how much the G force is on any given planet, you must know some things about the planet. First, what is its mass? The greater a planet's mass is, the stronger its gravitational pull will be. However, mass will not tell you everything. For example, the Earth has 80 times more mass than the Moon but only about 6 times its gravitational pull. The reason for this is that a planet's pull acts as if it starts at its center, not at its surface. And, because gravity decreases exponentially over distance, a planet's surface gravity will be weaker, the farther the distance is to its center. To determine how much the G force is on any given planet, you must know some things about the planet. First, what is its mass? The greater a planet's mass is, the stronger its gravitational pull will be. However, mass will not tell you everything. For example, the Earth has 80 times more mass than the Moon but only about 6 times its gravitational pull. The reason for this is that a planet's pull acts as if it starts at its center, not at its surface. And, because gravity decreases exponentially over distance, a planet's surface gravity will be weaker, the farther the distance is to its center. To determine how much the G force is on any given planet, you must know some things about the planet. First, what is its mass? The greater a planet's mass is, the stronger its gravitational pull will be. However, mass will not tell you everything. For example, the Earth has 80 times more mass than the Moon but only about 6 times its gravitational pull. The reason for this is that a planet's pull acts as if it starts at its center, not at its surface. And, because gravity decreases exponentially over distance, a planet's surface gravity will be weaker, the farther the distance is to its center. To determine how much the G force is on any given planet, you must know some things about the planet. First, what is its mass? The greater a planet's mass is, the stronger its gravitational pull will be. However, mass will not tell you everything. For example, the Earth has 80 times more mass than the Moon but only about 6 times its gravitational pull. The reason for this is that a planet's pull acts as if it starts at its center, not at its surface. And, because gravity decreases exponentially over distance, a planet's surface gravity will be weaker, the farther the distance is to its center.

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