Name __________________________________________________ Student ID _________________ 10/10/11 exam01a_au11_answerkey.doc 1 TA’s Name _______________________ Section _______ Date ______________ Nell Byler – AA, AB – 8:30 & 9:30 am Nick Hunt-Walker – AC, AH – 10:30 am & 3:30 pm Nicole Silvestri – AF, AG – 1:30 & 2:30 pm Ben Vega-Westhoff – AD, AE – 11:30 am & 12:30 pm Instructor’s name: Ana Larson CHECK NOW TO MAKE SURE YOUR NAME IS ON THIS EXAM AND THAT YOU HAVE 8 PAGES AND A TOTAL OF 18 QUESTIONS! PLEASE TURN OFF YOUR CELL PHONE RIGHT NOW! THANK YOU! All books, packs, cell phones, papers, Course Packs, etc. must be placed under your seat. We need room to come and go between rows. NO CALCULATORS ARE NEEDED. ALL CAPS OFF OR TURNED BACKWARDS. Please do not start this exam until directed to do so. You will not be allowed to leave the room once the exam starts, so make sure you are ready to go to work once the bell rings. Extra pencils, erasers, bathroom run, etc. should be considered right now. Any student who continues to work beyond the class bell will have 1 point deducted for every minute of overtime s/he uses. You are free to raise your hand during the exam and ask questions involving clarification of exam questions. Newton’s Laws • An object at rest stays at rest, an object in motion stays in motion unless acted upon by an outside force. • The acceleration of an object is directly proportional to the force exerted on it and inversely proportional to its mass; acceleration = force/mass or ! a =Fm (usually written as ! F = ma. • For every action there is an equal and opposite reaction; forces come in pairs. Gravity of a planet: ! Fgravity= GMmR2, F represents the force of gravity, G is the gravitational constant, M is the mass of the planet, m is the mass of the object on the surface, and R is the radius of the planet. Mathematical logic: What is done on one side of the equation must be balanced by doing the same thing on the other side.2 Wien’s Law ! T =2.9 "106#peak K; wavelength (λ) must be in nanometers and temperature (T) in Kelvins. kinetic energy = 1/2 mass velocity squared ! KE =12mv2 gravitational potential energy = mass acceleration due to gravity height ! GPE = mgh Energy (mass energy) = mass speed of light squared E = mc2 Electromagnetic radiation Energy (of a photon) = Planck’s constant frequency of light ! Ephoton= h" (or hf) Wavelength frequency = speed of light ! "#= c Lyman series (ultraviolet wavelengths) and Balmer series (visible wavelengths) for hydrogen. Balmer wavelengths shown: 656.3 nm 486.1 nm 434.1 nm 410.2 nmexam01a_au11_answerkey.doc 3 01. (5 pts) Fill in the blanks above with the appropriate label for the major structures of the Universe from our point of view. Choose from: planet, planetary system, star, galaxy, super-galaxy, local group, local galaxies, cosmic galaxy, universal supercluster, local supercluster. 02. (2 pts) Stars twinkle, planets don’t. Planets orbit stars. What is another, more important distinction between a star and a planet? A star shines from light generated by nuclear fusion in its core. A planet shines because it reflects light. PARTIAL CREDIT: 1 pt if get only 1 right. Energy generated from fusion; energy generated in the core OK.4 03. (3 pts) Would it ever be possible for a planetary system to contain a galaxy within it? Explain. No. Galaxies (A galaxy) contain(s) planetary systems, planetary systems don’t contain a galaxy. ALSO OK No. A planetary system contains only a star (or stars) and planets (and other stuff). Use the following sky map to answer the following 3 questions. You may also use your “Star and Planet Locator.” The solid curved line represents the celestial equator. Objects located on the celestial equator are “up” in the sky for 12 hours.exam01a_au11_answerkey.doc 5 04. (3 pts) The star map shows the night sky at 8 pm, PST, in early October, with Capricornus on the meridian. Why won’t we see Capricornus at 8 pm in early April? Be very clear in your explanation. We won’t see Capricornus in April because the Sun will be in the way. This is because the Earth orbits the Sun and the Sun thus appears to move against the background stars. PARTIAL CREDIT. 1 pt – Sun will be in the way; 2 pts – Sun will be in way + Earth orbits 05. (2 pts) The dashed line running through Sagittarius, Capricornus, Aquarius, and Pisces (to name a few) is called the __ecliptic____ and represents the path of the ___Sun____ against the stars. 06. (1 pt) Which of these three constellations – Hercules, Aquila, Pegasus – has yet to reach the meridian? ______Pegasus_____ Hercules Aquila Pegasus 07. (2 pts) Draco is a circumpolar constellation. What does circumpolar mean? The constellation (or stars) never set from your location (OK always see or up from where you live) 08. (3 pts) Seattle, Washington, USA, and Emba, Kazakhstan, have about the same latitude, but Emba is nearly opposite the Earth in longitude. Could residents of Emba use this star map? Explain. The stars (constellations, celestial objects) that we see depend on our latitude not on our longitude. ABOVE IS SUFFICIENT. [They may add something like “The celestial sphere is fixed, and the Earth turns within it. Only latitude matters. I’d be tempted to give a bonus point……] 09. (2 pts) Here are 2 identically sized planets (radii are equal), but one of them has 3 times the mass of the other. Your identical twin (your masses are equal) lives on the more massive planet, and thus feels a gravitational force that is _____ a. exactly the same as what you feel. ___XX__ b. three times what you feel. _____ c. nine times what you feel. _____ d. one-third as much as what you feel.6 10. (2 pts) We found during one of our lectures that if we weighed 150 lbs on Earth, we would weigh approximately 355 lbs on Jupiter, or a little over 2 times as much. Jupiter’s mass is about 318 times and its radius about 11 times that of Earth. With Jupiter being so massive, why wouldn’t we weigh 318 times as much on Jupiter (if, in fact, it had a surface we could stand on)? The larger radius compensates for the much greater mass. [The larger radius balances somewhat the larger mass.] [We have to also
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