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Conditions for equilibrium and Elastic Moduli
• The sum of all forces present in the x, y, and z directions are each distinctly equal to zero.
• The sum of all torques for any given point are equal to zero.
Sheer stress and strain • Take your textbook and push on the top cover while the rest
remains on a tabletop. Notice the angular distortion.
Newton’s Law of Gravitation
• The gravitational force is always attractive and depends on both the masses of the bodies involved and their separations.
Gravitational force changes densities below sea level
• Just as it’s interesting to remember that all gravitational forces are calculated from the center of the planet, it’s interesting to follow the density as one proceeds from crust to mantle to core.
Gravitational potential energy • Objects changing their distance from earth are also
changing their potential energy with respect to earth.
Simple harmonic motion: • An ideal spring responds
to stretch and compression linearly, obeying Hooke’s Law.
• For a real spring, Hookes’ Law is a good approximation.
Simple harmonic motion viewed as a projection
• If you illuminate uniform circular motion (say by shining a flashlight on a candle placed on a rotating lazy-Susan spice rack), the shadow projection that will be cast will be undergoing simple harmonic motion.
Dinosaurs, long tails, and the physical pendulum
• The stride of Tyrannosaurus rex can be treated as a physical pendulum.
Forced (driven) oscillations and resonance II
• The Tacoma Narrows Bridge suffered spectacular structural failure after absorbing too much resonant energy
Vocabulary: • Illumination=Işıklandırma • Abstract =Özet • Shine=Parlaklık • Flashlight =El feneri • Shadow = Gölge • Back and forth =İleri-Geri • Phase=Faz • Amplitude=Genlik • Stride =Adım • Damped oscillations=Sönümlü titreşimler • Driving force=itici güç • Undamped =Sönümsüz • Broaden=Genişletmek • Sharp=Keskin • Absorb =Emmek • Shift=Değişiklik • Artifical=Yapay • Forced oscillations=Zorla Salınımlar • Tendency=Eğilim • Apparatus=Cihaz, Malzeme
• Moduli=Modül • Equilibrium conditons=Denge koşulları • Tensile=Gerilme • Stress=Zor • Strain=Zorlanma • Attractive =Çekici • Sheer=Sapma • Angular distortion =Açısal Bozulma • Involve=İçermek • Solid inner core=Katı bir iç çekirdek • Molten outer core=Erimiş bir dış çekirdek • Mostly solid mantle= Çoğunlukla katı kabuk • Curved path= Kavisli yol • Straight path=Düz yol • Satellite Motion=Uydu hareketi • Orbit=Yörünge • Ordinary star=Sıradan bir yıldız • Accretion=Büyüme • Intense=Şiddetli • Simple harmonic motion=Basit harmonik hareket