ASTR 1020 1st Edition Lecture 1 Outline of Last Lecture I. No previous lectureOutline of Current Lecture I. Our Place in the UniverseA. DistancesB. The ScaleC. MotionD. GravityE. Momentum & ForceCurrent LectureI. Our Modern View of the UniverseEarth is a planet in our solar system which consists of moons, asteroids, comets, and other planets with the Sun at the system’s center. A. Distances - An astronomical unit is the average distance between the Earth and Sun. (1.5 x 108km=1 AU ¿- A Parsec is the typical distance between stars as defined the angular wobble caused by Earth’s orbit. (3.1 x 1013km ¿- A light-year is the distance light can travel in one year. (9.5 x 1012km¿B. ScaleOn a 1-10 billion scale, the Sun would be the size of a grapefruit and Earth the size ofa ballpoint in a pen. Destination Light Travel TimeMoon 1 secSun 8 minVega (nearby star) 25 yearsAndromeda Galaxy 2.5 million yearsC. Motion- Speed: rate at which object moves These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-ms2speed=distancetime¿)- Velocity: speed & direction- Acceleration: change in velocity units of speed/time D. Gravity- All falling objects accelerate at the same rate (not counting resistance)- On Earth g= 10 ms2 speed increases to 10 m/s with each second of falling- Galileo showed that g is the same for all falling objects regardless of their massE. Momentum & Force- Momentum: Mass x velocity- Net Force: Changes momentum, causing acceleration- Rotational momentum of a spinning or orbiting object is known as angular momentum.Angular momentum = mass x velocity x distance from axis- Mass: amount of matter in an object- Weight: the force that acts upon an object; depends on acceleration of gravity and any other
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