Radio telescopes are telescopes used for the detection of radio emission from space. Because radio waves have much longer wavelengths than visible light, the diameter of a radio telescope must be very large to provide good resolution. For example, the radio telescope in Penticton, BC in Canada, has a diameter of 26 m and can be operated at frequencies as high as 6.6 GHz. (a) What is the wavelength corresponding to this frequency? (b) What is the angular separation of two radio sources that can be resolved by this telescope? (c) Compare the telescope’s resolution with the angular size of the moon.
Chapter6TextbookOutline 6-1Newton’sLawsinamessyWorld Ø Thisbriefsectiontalkedabouttheforcesthatwillaltertheresults ofNewton’sLawsintherealworld 6-2FrictionandtheNormalForceRevisited Ø Friction:forceactingontwosurfaceswhentheyarerubbed together;canbereducedbutneverfullyeliminated o Withoutfriction,wewouldnotbeabletowalkonthe ground,driveacar,orpetadog o Frictioniswhatholdsupaboxifyoupushitdirectlyintoa wallandhavenothingbelowittosupportthebox;itisthe componentparalleltothewall o Thenormalforceisthecomponentofforcepointingdirectly inthewall Ø Frictioniscausedbytheedgesofeachobjectsactuallybeing jaggedinsteadofasmoothsurface o Realcontactareasarethejaggedpartsofeachsurfacethat actuallytough o Apparentcontactareasarethegapofairinbetweenthe contactareas o Polishingdownasurfacetomakeitmoresmoothwill actuallyincreasethemagnitudeofthefrictionforcebecause itwillincreasetheamountofcontactare o Youcanslightlyreducefrictionbetweentwoverypolished surfacesifyousprinklesomepowderbetweenthem o Twoextremelypolished,cleansurfacespushedagainstone anotherinavacuumcanbondandbecomestucktogether duetothehighamountofcontactar
