AstrophysicsM - 1. (a) Size of Universe Time Open Flat...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1. (a) Size of Universe Time Open Flat Closed 3 max Award [1] for each correct label. (b) 3 max Type of Universe Relation between and Open < Flat = Closed > Award [1] for each correct entry. [6] 2. (a) the universe is expanding; 1 (b) any sensible straight line; 1 (c) Slope of the graph; 1 (d) T = H 1 ; correct conversion of units to get T 10 10 years; 2 [5] 3. (a) cosmic background radiation is microwave radiation; filling the universe / from all directions; 2 Award other relevant and appropriate comments eg at a temperature of about 3K or left over from the Big Bang. 1 (b) the Big Bang predicts an expanding universe that had a very high temperature at the beginning; during the expansion the universe is cooling down and the temperature of the radiation should fall to its present low value, (which is precisely what the cosmic 2 background radiation measures); or Big Bang producing initially very short wavelength photons / em radiation; as the universe expands, the wavelengths become redshifted / longer (to reach current value); 2 (c) the redshift in the light observed from distant galaxies (indicating that they are moving away from each other) / the helium abundance in the universe which is about 25% and is consistent with a hot beginning of the universe;1 Note : question asks for evidence so do not accept universe is expanding unless the answer mentions redshift etc. (d) the student is wrong; space is created as the universe expands / there is no outside to the universe; 2 Award [0] if no explanation or incorrect explanation. [7] 4. (a) Diagram should show spiral arms; central disc; the solar system on one of the arms about a third of the way from the centre; 3 Be generous in the position accept between 4 1 and 4 3 . (b) c v c v =- = 658 658 670 ; hence v = 658 658 670- c = 0.018 c = 5.47 10 3 km s 1 ; 2 Award [1 max] for 670 658 670- = 0.0179. 2 (c) (i) straight-line; through origin; 2 (0,0) v d (ii) relative speed of two points in the universe separated by distance d is v = T d where T is the age of the universe / argument to show v = T d ; v = T d = H d therefore T = 1 H ; 2 Award [0] for answers that just show that T = H 1 has the right units. (iii) the Hubble constant is obtained from the slope of the graph; 1 [10] 5. (a) if less than , Universe will expand for evermore; if greater than , Universe will expand; and then contract; 3 (b) (i) substitution to give = 1.3 10 26 kg m 3 ; 1 (ii) number density = ) 10 66 . 1 ( ) 10 3 . 1 ( 27 26-- , about 7 or 8 m 3 ; 1 Note : unit is m 3 . [5] 3 6. (a) (i) N on line between 10 2 s and 10 3 s; 1 (ii) G labelled on line at about 10 13 s; 1 Award 10 12 s to 10 14 s....
View Full Document

This note was uploaded on 09/21/2009 for the course PHYSICS 2211 taught by Professor Uzer during the Fall '08 term at Georgia Institute of Technology.

Page1 / 15

AstrophysicsM - 1. (a) Size of Universe Time Open Flat...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online