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PHYS 1001
Physics and the Modern Society

Midterm Examination
Suggested Solutions
Date: 30 October 2012
Time: 12:05 pm C 1:15 pm (1 hour 10 minutes)
Venue: LTD

Student Name:


Student ID:


Tutorial Group:
T1 / T2 / T3 / T4 ( Wed / Fri )

Total Scores:
/ 212

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DO NOT TURN OVER UNTIL YOU ARE TOLD TO DO SO.




Multiple-Choices (8 questions, 5 marks each)
Circle one answer in each question.

1. Which of the following equations gives a WRONG relationship among the units?

A. N = kg.ms.2. (Hint: force)

B. W = J.s.1. (Hint: power)

C. J = N.m. (Hint: work done)

D. Sv = J.kg. (Hint: radiation dose)




2. Ignoring quantum effects, at absolute zero,

A. molecules stop vibrating.

B. an atom shrinks to zero volume.

C. temperature = .273.15 K.

D. all matter becomes plasma.




3. Regard a refrigerator as a heat pump. In a closed room, an operating refrigerator with its door open will _____ the room temperature in the long run.

A. decrease

B. not change

C. increase

D. Insufficient information to determine.




4. An astronaut (inside a space capsule) orbiting the Earth feels weightless because

A. the astronaut has zero mass in outer space.

B. the astronaut is free-falling with the space capsule towards the Earth.

C. the Earth exerts no gravitational pull on the astronaut.

D. None of the above.













5. In Fig. 1, a heavy sphere is hung from a support by a string, and another identical string is attached to the bottom of the sphere (Assume all points of attachment are firm). When a downward jerk is applied to the lower string, only the lower string breaks. Which law of motion explains the above observation?

A. Newtons First Law.

B. Newtons Second Law.

C. Newtons Third Law.

D. None of the above.






6. A radioactive source can be analyzed, by a magnetic field, into two distinct types: alpha and beta particles. Why the path of the beta particles is more deflected than that of the alpha particles?

A. Because alpha particles experience larger gravitational pull.

B. Because alpha particles carry positive electric charges.

C. Because beta particles are less massive.

D. Because beta particles possess higher kinetic energies.




7. Which of the following pairs of nuclides (i.e., nuclei having specific numbers of protons and neutrons) are NOT isotopes?

A. Carbon-12 and carbon-14.

B. Deuterium and tritium.

C. U-235 and U-238.

D. Potassium-40 and argon-40.




8. The high voltage of 275 kV in overhead power lines is stepped down by a transformer to 220 V for domestic use. Calculate the turns ratio in the transformer, number of turns in primary coil : number of turns in secondary coil.

A. 1.25 : 1.

B. 55 : 1.

C. 1250 : 1.

D. Insufficient data to determin