19_light_IV.pdf

Mid Semester Survey ? Due on Friday (Oct. 9th) at 1pm. ? Posted under the ?Assignments? section of Blackboard. ? This will help me improve the class. ? Answer honestly, all replies are anonymous ? You must finish every question to get credit. ? You must hit the submit button to get credit. Questions from your last participation: What did I not understand from class? ? ?I still don?t quite understand the relation between force and acceleration.? ? Acceleration: How fast the velocity of something is changing. ? Force: How hard an object must be pushed to cause a certain acceleration, given its mass. force = mass x acceleration Questions from your last participation: What did I not understand from class? ? ?What causes some things to orbit and some things to collide?? These objects will definitely collide Questions from your last participation: What did I not understand from class? ? What causes some things to orbit and some things to collide? How about these objects? Questions from your last participation: What did I not understand from class? ? What causes some things to orbit and some things to collide? And these objects? It depends on their relative velocities, masses, and sizes Questions from your last participation: What did I not understand from class? ? ?I don?t understand how to calculate force and acceleration between objects.? ? I will post an additional explanation for the quiz questions online. If you are still confused: ? do the mastering astronomy tutorials ? come to my office hours and ask for help!! Questions from your last participation: What did I not understand from class? ? ?I do not understand the difference between the different kinds of energy.? ? Energy is the ability to do work. ? What happens to the car as the weight falls down? Questions from your last participation: What did I not understand from class? From which height should the weight be dropped to accelerate the car to the highest velocity? A B C D. All heights will give the same result. A B C Questions from your last participation: What did I not understand from class? At which height does the weight have the least gravitational potential energy? A B C D. All heights have the same gravitational potential energy A B C Questions from your last participation: What did I not understand from class? Assuming there is no friction, what happens to the total energy of the car and weight together? A. increases B. decreases C. stays the same. A B C 12 What happens to the kinetic energy of the planet as it moves around the star? A. increases B. decreases C. stays the same. 12 What happens to the gravitational potential energy of the planet as it moves around the star? A. increases B. decreases C. stays the same. 12 What happens to the total energy of the planet as it moves around the star? A. increases B. decreases C. stays the same. Give an example of how radiative energy (light) be used to do work on an object? Solar powered cars! Converting the suns energy into motion! Back to light Use the graph to determine which of the two stars (A or D) gives off more green light? a) Star A b) Star D c) They both give off the same amount of green light. Use the graph at right to determine which of the two stars (A or C) is at a higher temperature? a) Star A b) Star C c) The two stars have the same temperature. d) It is not possible to infer this relationship. Use the graph to determine which of the following relationships is possible to infer about stars A and C based on the information provided in the graph. a) Star A is smaller than Star C. b) Star A is larger than Star C. c) The stars are the same size. d) All of the above are possible. e) It is not possible to infer any of these relationships. A B C VIBGYOR Which of the following are smaller than C? A. A B. B C. A and B D. Neither A nor B E. There is not enough information to determine this A B C VIBGYOR Which of these objects is the smallest? A. A B. B C. C D. They all have the same size. E. There is not enough information to determine this How can we use light to learn about the Universe ? Temperature ? We can learn about density and chemical composition! ? Because light interacts with atoms. But where does light come from? Electromagnetic radiation is caused by accelerating charged particles! But radiation can also cause charges to accelerate. First, a little about atoms. An atom consists of a small, dense nucleus (containing protons and neutrons) surrounded by electrons - Model Proposed by Niels Bohr 1913 A nucleus is about 10 -15 m in size and the first electron orbits out at 10 -10 m from the center of the atom ? The size of the electron orbit is 100,000 times greater than the size of the nucleus Atoms are mostly empty space So if a nucleus the size of an orange (10 cm) was located at the center of the football field, where would the electron be? End Zone? Grandstands? On Campus? In Lawrence? In Topeka? Atoms are mostly empty space If the electron?s orbit is 100,000 times bigger than the nucleus then the electron would be 10,000m or 6.21 miles away from the center of the Football Field! On the northwest edge of town, by K10 and 6th. Atoms are mostly empty space The electron should be thought of as a distribution or cloud of probability around the nucleus that on-average behave like a point particle on a fixed circular path Greg Rudnick The Universe, a brief overview?