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Physics 002 Final Examination 29 May, 2001.
Time allowed: 90 minutes Total: 80 marks
A
Data table:
1 parsec
3.26 light years
1 parsec
206,265 AU
Orbital radius of Earth
1.50 1011 m
Speed of light
3 108 m/s
Universal gravitational constant
6.67 10-11 N.m2/kg2
Mass of Sun
1.99 1030 kg
Part A Multiple choice (35 marks):
(1)
Which of the following statements are, or are consequences of, the postulates of special or general relativity?
A. Observers can detect their uniform motion by measuring the relativistic Doppler effect of distant stars.
B. Observers can distinguish between the effects of accelerations and gravitational forces by observing the gravitational red shift.
C. The law of universal gravitation is modified when an observer falls within the event horizon of a black hole.
D. The speed of light in the vacuum is the same constant for all observers independent of their motion relative to the light source.
E.
The acceleration of an object is proportional to the applied force and inversely proportional to its mass.
Ans. D
(2)
Which of the following observations DO NOT support the assertion that pulsars are neutron stars?
A. Their pulses are short.
B. They are strong energy sources emitting radio waves, X-rays and gamma rays.
C. They are located inside supernova remnants.
D. Pulsars in binary systems show that they are more massive than white dwarfs.
E. They are strong emitted neutron sources. Ans. E
(3)
A 10-solar-mass black hole has an average density of 1014 times that of water. The average density of a 109-solar-mass black hole is closest to _____ times that of water.
A.
10-4
B.
10-2
C.
10
D.
105
E.
106 Ans. B
(4)
The most likely classification for the galaxy below is
A.
E2
B.
E5
C.
SBa
D.
Sb
E.
Irr Ans. B
(5) Which is a property of quasars?
A.
They emit hot jets of neutrinos, which cause the formation of double-lobed radio sources.
B.
Supernova explosions are observed in their host galaxies.
C.
They are often located in the tails and bridges formed during collisions of galaxies.
D.
Their light intensity often fluctuates as fast as several cycles per second.
E.
Photon emissions of the hot gases around them cannot escape from the gravitational influence of the quasars.
Ans. B
(6) Which of the following will happen in a spatially flat universe?
A.
The cosmic expansion will eventually stop.
B.
The density of the universe will always be constant.
C.
A Big Crunch will occur some time in the future.
D.
The area of a triangle will be equal to . base x height.
E.
None of the above.
Ans. D
(7)
Which of the following is true about the Hubble