What are mechanical waves? What do you think waves carry? Can you see waves? Examples?

1. What are mechanical waves? What do you think waves carry? Can you see waves? Examples?

2. Mechanical Waves • Mechanical wavesare disturbances in matter that carry energy from one place to another. • Usually require matter through which to travel • The matter a wave travels through is called a medium. • Medium can be a solid, liquid, or gas • Some waves can travel through space…with no medium!

3. Transverse and Longitudinal WaveWhich is which?

4. What happens when… • A wave meets a hard surface like a wall? • Reflection • A wave enters a new medium? • Refraction • A wave moves around an obstacle? • Diffraction

5. Axis An imaginary line which runs through both poles of a planet.

6. Rotation of the Earth • The Earth is spinning upon a central axis. • The Earth's axis is tipped over about 23.5° from the vertical. • The Earth rotates around once in 24 hours.

7. Rotation of the Earth http://www.classzone.com/books/earth_science/terc/content/visualizations/es0404/es0404page01.cfm?chapter_no=visualization

8. Revolution of the Earth • The earth revolves around the sun. • The orbit is elliptic. • The Earth's tilt stays constant. • The Earth completes one revolution in 365 days.

9. Phases of the Moon

10. Shoot for the moon. Even if you miss, you'll land among the stars. ECLIPSES • A solar eclipse is when an object in space casts a shadow from the sun on another object in space. • A lunar eclipse occurs when the Earth blocks the sunlight from reaching the moon. Question: Why do lunar eclipses occur only during full moons? Answer: That is the only time that the earth comes between the moon and sun. Question: Why don’t we have a lunar eclipse every full moon? Answer: The tilt of the moon’s orbit is 5° different than the earth Answer: The light from the sun gets bent as it passes through our atmosphere causing it to appear red. Question: Why does the full moon appear to be red during certain times of the year?

11. Magnetic Fields The region where the magnetic forces act is called the “magnetic field”

12. All magnetic phenomena result from forces between electric charges in motion.

13. Charges • Matter is made of atoms • Atoms are made of sub-atomic particles • Protons are positively charged • Electrons are negatively charged • Atoms are electrically neutral • This means positive charges equal negative charges

14. Charging the Atoms Electrons are loosely held by atoms of some materials These electrons can be moved Loosing these electrons makes the atoms electrically charged Friction, conduction, and induction are three ways atoms can be charged

15. Static Electricity • Static electricity is the build up of electric charges on an object • Electrons move off an object to another causes the ELECTRIC DISCHARGE • Lightening is a wonderful and exciting example of this phenomena

16. Current Electricity • Some materials allow the charges to move freely through them • These materials are called conductors • Some examples of conductors are copper, iron, aluminum, and zinc

17. Insulators • These materials do not allow the charges to move freely through them • These materials are called the insulators • Some examples of insulators are rubber, plastic, and wood

18. Facts about Magnets 1. There are North Poles and South Poles. 2. Like poles repel, unlike poles attract. 3. Magnetic forces attract only magnetic materials. 4. Magnetic forces act at a distance. 5. While magnetized, temporary magnets act like permanent magnets.

19. Some More Facts 9. A charged particle experiences no magnetic force when moving parallel to a magnetic field, but when it is moving perpendicular to the field it experiences a force perpendicular to both the field and the direction of motion. 10. A current-carrying wire in a perpendicular magnetic field experiences a force in a direction perpendicular to both the wire and the field.

20. Series and parallel circuits Series Circuit Parallel circuit

21. Air pressure is the result of the column of air that is above you. There is so much air above you that at sea level you have 14.7 lbs/in2 pushing on you. Gravity causes most of the air to be pulled down to the surface. Air Pressure

22. As the air pressure decreases, the density of the air decreases. The air particles are not squashed together as tightly the higher one goes. This is caused by gravity! The air at sea level and at 6km has the same 21% oxygen, but at 6km there are fewer molecules, so you take in less oxygen with each breath. Shows density of air Altitude and Density

23. Layers in a different diagram

24. Troposphere: temperature at surface is warmed by the earth absorbing energy from the sun. Air cools as it rises (air molecules lose energy) The air cools by about 6.5°C for every 1-km above the ground. In 10 KM air will cool 6.5*10=65 Temperature and the Troposphere

25. Ozone absorbs ultraviolet radiation from the sun, causing the temperature to increase. Temperature and the Stratosphere

26. This layer does not absorb energy from the sun, so it starts to cool again. Without greenhouse gases, energy pretty much passes straight through! Temperature and the Mesosphere

27. Solar radiation first hits this layer, so the few particles that are here can gain lots of energy. They move rapidly, so they have a very high temperature. But the air is so thin here that it takes special instruments to measure the temperature accurately. So even though it is very hot (over 1000°C), it would feel cold because there are so few particles to transfer heat to you. Temperature and the Thermosphere

28. The Troposphere • Lowest (inner) layer • weather occurs here • we live in it. • “tropo” means turning or changing conditions • depth varies from 9km above the poles to 16km at the equator • shallowest (least thick) layer, but contains most of the mass (90%).

29. The Stratosphere • “strato” means layer or spreading out • Contains the ozone layer which absorbs energy and causes the temperature to rise • The ozone layer protects the surface from dangerous UV rays

30. Drop in temperature marks beginning of mesosphere “Meso” means middle Most meteors burn up here The Mesosphere

31. The Thermosphere • Very top layer • Air is very, very thin, about 1/1000th as dense as the air at sea level • “Thermo” means heat • Extends from 80km to space • No definite outer edge • Very hot (over 1000°C), but since air is so thin it would not feel warm at all. • Divided into two parts, the ionosphere and the exosphere

32. The Ionosphere • Energy from sun strips the electrons from the gas molecules creating charged particles called ions. • Radio waves can bounce off of ions, allowing radio waves to travel great distances. • The aurora borealis (Northern Lights) occur here

33. The Exosphere • “Exo” means outer • Extends for 1000’s of miles • Satellites orbit here • No definite edge • Molecules gradually escape out into space