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(PHYS002)finalaaa_f03.pdf
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Physics 002 Final Examination 20 December, 2003.
Time allowed: 90 minutes Total: 70 marks

Name:

Student ID:
A




Data table:
1 parsec (pc)
3.26 light years

1 parsec (pc)
206,265 AU

Speed of light
3 108 m/s

Universal gravitational constant
6.67 10-11 N.m2/kg2

1 Astronomical Unit
1.50 1011 m

Mass of Sun
1.99 1030 kg

1 radian
206,265 arc sec




Section
Marks

A


B


C1


C2


Total





Section A: Multiple choice (20 marks):

(1) What is the end state of a medium size main sequence star like our sun?
A.
Brown dwarf.


B.
Red dwarf.


C.
Neutron star.


D.
Black dwarf.


E.
Black hole. Answer:________




(2) Pulsars are believed to slow down because
A.
they are converting energy of rotation into radiation.


B.
there are internal disturbances similar to earthquakes.


C.
there is friction with the interstellar medium.


D.
angular momentum must be conserved.


E.
their mass is decreasing. Answer:_____ __




(3) Where would a supernova explosion most likely occur?
I.
in an elliptical galaxy


II.
in the disk of a spiral galaxy


III.
in the halo of a spiral galaxy



A.
I only


B.
II only


C.
III only


D.
II & III


E.
! & III Answer:________





(4) In Special Relativity,
A.
the speed of light is the same in all media.


B.
length is contracted in any frame.


C.
time is dilated in any frame.


D.
mass of an object remains the same independent of its speed.


E.
the time of an event depends on the inertial reference frame in which it is measured. Answer:________




(5) Which of the following is NOT evidence that quasars are active nuclei of distant galaxies?
$1: Supernova explosions can be observed near both quasars and active nuclei of distant galaxies.
$2: Light from quasars may contain absorption spectral lines whose redshifts may be due to the absorption by galaxies distant from Earth. The same is possible for active nuclei of distant galaxies.
$4: Jets can be observed to emanate from both quasars and active nuclei of distant galaxies.
$8: Both quasars and active nuclei of distant galaxies are more frequently observed in colliding galaxies.

What is the dollar value after adding up those for the correct answers?
Answer:___ ___




Section B: True and False (14 marks):

(1-8) Read carefully the following italicized paragraphs abridged from Scientific American. The theme is about the age of the universe.

Hubble and other pioneers estimated distances to various galaxies by assuming that the ones that appeared bright were comparatively close, and the ones that appeared dim were far away. But this methodology works only crudely, because galaxies differ in their pr