ASTR 1020 1st Edition Lecture 2 Outline of Last Lecture I. Our Place in the UniverseA. DistancesB. The ScaleC. MotionD. GravityE. Momentum & ForceOutline of Current Lecture I. Motion & EnergyA. Newton’s LawsB. Basic Types of Energy & Laws Current LectureI. Motion & EnergyA. Newton’s Laws 1. An object on motion stays in motion unless acted upon by a net force2. Force = mass x acceleration3. Every action has an equal and opposite reactionB. Basic Types of Energy & Laws- Kinetic (motion)= 12mv2M = massV = velocity- Thermal Energy: a measure of the total kinetic energy of all the particles in a substance.- Depends on temperature and density- Temperature: measures average kinetic energy of the many particles in a substance- Radiative (light)- Photons have energy hcwavelength❑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.H = Planck’s constantC = speed of light- Stored or potential- Gravitational Potential Energy: Depends onAttracting massObject massDistance from center of attractorOn Earth, depends onObject mass (m)Strength of gravityHeight (h) object could potentially fall from- Conservation of energy: energy can be changed but not destroyed.- Universal Law of Gravitation1. Every mass attracts every other mass2. Attraction is directly proportional to product of other masses3. Attraction is inversely proportional to the square of distance between centers.Fg=GM1M2d2❑- Newton’s Version of Kepler’s 3rd Law1.M1+M2¿ p¿¿M1+M2=∑of masses(solar mass)P = orbital period (year)A = average orbital distance (AU)- Useful for any two objects on space- Kepler’s Other Laws- Planets move faster when closer to the sun (k’s 2nd law)- Total orbital energy (gravitational and kinetic) stays constant if there is no external
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