Welcome Back Minions!!!

1. Welcome Back Minions!!!

2. Recap: What are waves? • A wave is a disturbance that carries energy through matter and space. • The matter through which waves move through is called a MEDIUM. It can be a solid, liquid or gas.

3. Mechanical Waves • Waves that require a medium are called mechanical waves. • Nearly all waves are mechanical waves. Ex: ocean waves, sound waves and seismic waves (earthquakes) • Electromagnetic Waves are NOT mechanical waves, so they do not need a medium to travel through!

4. Energy moving through a medium • The picture above shows a medium made up of particles connected by springs.  • As one individual particle is disturbed, it transfers the energy from that particle to the next and so on. • So… energy is transported from one end of the medium to the other end of the mediumwithout transporting any actual matter!  • Ex: Like being in the ocean and a wave picks you up and puts you down as it passes by. • Or Dominoes falling into each other

5. How mechanical waves move through matter… • The kind of medium, (solid, liquid, gas) determines the mechanical wave speed. • Waves rely on the elasticity and inertia properties of the medium. • Basically how are the particles moving in the medium? • Which medium do mechanical waves travel faster in, solids, liquids or gases? (*hint* think about molecules)

6. How mechanical waves move through matter… • Solid mediums! Because.. in solids and liquidsthe molecules are more closely packed together than gases, so energy is transferred from one particle to another particle faster. • So which medium do mechanical waves travel through the slowest? • Gases! Because… the particles are moving rapidly and randomly it is hard for the particles to transfer the energy to one another!

7. Faster than the Speed of Sound! • In the air, sound will generally travel 300 meters per second. • In the liquids, sound will generally travel 1500 meters per second. • In the solids, sound will generally travel 2500 meters per second.

8. Bouncing back… • Echo • A reflected sound wave. • Harder/Smoother surface, better echo • Softer/Uneven surface, not as good or none.

9. Echo • Uses • Fish Finder • Cardiogram • Ultrasound • Detect/Measure Earthquakes • Echolocation • SONAR

10. Using waves to detect defects in man-made structures. Break in the rail line

11. Ever notice… • Ambulance coming towards you, then driving by and going away from you… • What did you notice?

12. Doppler Effect • Doppler Effect • The change of a frequency of a wave as the source moves in relation to the observer. • If moving towards the observer… • Frequency increases. (Higher Pitch) • If moving away from observer… • Frequency decreases. (Lower Pitch)

13. Doppler Effect • Explain to me how it works…

14. Breaking the Sound Barrier

15. Faster than the speed of sound… • You have seen the pictures…

16. The sound that goes boom… • Sonic Boom • Explosive sound when a shockwave reaches your ears. • Faster than speed of sound • Overcome compressed soundwaves

17. Shocking! • Shockwave • Overlapping soundwaves that result in a mechanical wave with high pressure and high energy.