Transcript Day_15
ASTR-1010 Planetary Astronomy Day - 15 ClassAction Stuff • Gravity Stuff • Splash page warm up Announcements Homework Chapter 3: Due Wednesday Feb. 24 Smartworks Chapters 4 & 5 are also posted Exam 2 will cover chapters 3, 4, & 5 There is a new discussion board question posted. Ranking Task (Kepler’s laws) due now. Ranking Task (Gravity) due Monday at classtime. 1st quarter observing night: Either Monday or Wednesday …based on weather. Isaac Newton (1642 – 1727) The Baddest Dead White Guy of Them All Isaac Newton (1642 – 1727) is known for 1. First observations of the sun 2. First sun centered scientific model of the solar system or universe 3. Being the world’s best naked-eye astronomer 4. Creating first a theoretical model to explain planetary motions 5. Creating first theoretical model for explaining gravity and ….. Isaac Newton (1642 – 1727) is known for 1. First observations of the sun 2. First sun centered scientific model of the solar system or universe 3. Being the world’s best naked-eye astronomer 4. Creating first a theoretical model to explain planetary motions 5. Creating first theoretical model for explaining gravity and ….. Isaac Newton formulated three laws of motion and the law of gravitation – these laws describe the motion of our physical world Newton’s Three Laws of Motion First Law - A body remains at rest or moves in a straight line at a constant speed unless acted upon by an outside (net) force. Second Law - (net) Force = mass x acceleration Third Law - Whenever one body exerts a force on a second body, the second body exerts an equal and opposite force on the first body. ClassAction Stuff • • • • Gravity Stuff Newton Law animation Gravity calculator Splash pages 11-23 Newton’s First Law • A body remains at rest or moves in a straight line at a constant speed unless acted upon by an outside (net) force. • A rockets will coast in space along a straight line at constant speed. • A hokey puck glides across the ice at constant speed until it hits something Newton’s Second Law of Motion • (net)Force = mass x acceleration or Fnet = m x a • Acceleration is the rate of change in velocity – or how quickly your motion is changing. • Three accelerators in your car!! Newton’s Third Law of Motion • Whenever one body exerts a force on a second body, the second body exerts an equal and opposite force on the first body. • Don’t need a rocket launch pad! • The Bug and the Windshield – who is having the worse day? Newton’s Three Laws of Motion - Review First Law - A body remains at rest or moves in a straight line at a constant speed unless acted upon by an outside (net) force. Second Law - (net) Force = mass x acceleration Third Law - Whenever one body exerts a force on a second body, the second body exerts an equal and opposite force on the first body. Newton’s Law of Gravitation • Newton’s law of gravitation states: Two bodies attract each other with a force that is directly proportional the product of their masses and is inversely proportional to the square of the distance between them. Gm m 1 2 F grav 2 d What the ….? I thought I understood gravity? Isaac Newton (1642 – 1727) - 1.Probably died a virgin 2.Was a priest and Lawyer 3.Had artificial wooden and silver noses 4.Probably died of Mercury poisoning 5.Rumored to have died when his bladder burst 6.Was blind at the time of his death 7.Was labeled a heretic by the church Isaac Newton (1642 – 1727) - 1. 2. 3. 4. 5. 6. 7. Probably died a virgin Was a priest and Lawyer Had artificial wooden and silver noses Probably died of Mercury poisoning Rumored to have died when his bladder burst Was blind at the time of his death Was labeled a heretic by the church Newton’s Law of Gravitation • To figure out the gravitational force just multiply the mass of the two things together then divide by the distance they are apart (squared). m1 Gm m 1 2 F grav 2 d d m2 Newton’s Law of Gravitation • Newton’s law of gravitation states: Two bodies attract each other with a force that is directly proportional the product of their masses and is inversely proportional to the square of the distance between them. Gm m 1 2 F 2 grav d 2 Nm 11 24 6 . 67 10 5 . 97 10 kg m object 2 kg F grav 6 2 6 .38 10 m F gm grav g ~ 10 m/s2 “the acceleration of gravity” And g x m is your weight!! Newton’s Law and Gravitation • All my favorite Projectiles behave like this!!! Velocity Acceleration Force Newton’s Laws and Kepler's Laws • Newton’s law of gravitation and his three laws of motion prove all of Kepler’s laws Newton's friend Edmund Halley predicted the comet would return in 1758 and it did! Lecture Tutorial -- pg. 29 Gravity and Newton's Laws • Work with a partner! • Read the instructions and questions carefully. • Discuss the concepts and your answers with one another. • Come to a consensus answer you both agree on. • If you get stuck or are not sure of your answer, ask another group. • 10 MINUTES Newton’s Law of Gravitation • To figure out the gravitational force just multiply the mass of the two things together then divide by the distance they are apart (squared). m1 Gm m 1 2 F grav 2 d d m2 Exam 1 •Exam 1 statistics: •N = 86/89 •Average = 57.2 •Median = 61 •Mode = 70 •Stddev = 18.8 •High = 88 •Low = 29