1. What is a sonic boom? • When an object which puts out sound travels faster than the speed of sound, the crests of the sound wave add up and reach an observer’s ears all at once. • Since the waves add up, the AMPLITUDE is much larger and the sound is LOUDER. Thus, we call it a sonic BOOM!

2. What is scientific notation? • Scientific notation is a way to deal with REALLY BIG and really small quantities. • The power of ten tells you where to put the decimal point! • 5 x 10-3 = 0.005 • 5 x 10-2 = 0.05 • 5 x 10-1 = 0.5 • 5 x 10-0 = 5. • 5 x 101 = 50. • 5 x 102 = 500. • 5 x 103 = 5000. • For example, the distance from the Earth to the Sun is • 150,000,000,000 meters (“One hundred and fifty billion meters”) • OR • 1.50 x 1011 meters (“One point five times ten to the eleventh meters”) • …But it is much easier to do calculations with scientific notation!

3. Why is resonance important in real life? • Technology: • We must know resonant frequencies of swaying skyscrapers to avoid wind blowing it over! • Tiny tuning forks provide the timer that runs your watch! • Science: • The frequency of oscillations of the surface of the sun or earth help us figure out what’s inside!

4. Are there multiple universes? • One idea for the origin of the universe is a “vacuum fluctuation” which “popped” out of nothingness and expanded to become our universe. Why couldn’t this happen more than once? • Support for this idea: • Quantum mechanics (physics of the very small) predicts these “vacuum fluctuations” • BUT… • We still aren’t quite sure how gravity works on small scales, so we don’t totally understand what would go on during this fluctuation. • We could never go to these universes, anyway, so it’s more a question of philosophy than of physics!

5. Why shouldn’t you stare at the sun? • Your retina (back of the eye) has cells which are sensitive to different frequencies of light, just like your cochlea (inner ear) has cells which are sensitive to different frequencies of sound! • If very bright (high amplitude) light is focused on the retina, you start to “cook” these cells and they can die! Without these cells, you cannot see!