Transcript 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