GEM2507
Physical Questions from
Everyday Life
Test 1
1. This is an OPEN BOOK test.
2. This paper contains THIRTEEN questions and SIX pages.
3. Full mark for each question is as indicated.
4. The total number of marks for this test is 20.
5. Answer ALL questions.
6. Write ALL the answers in THIS BOOK.
7. Always us SI Units
MATRIC No.
Do not write below this line!
Marks for questions:
Question
1-8
9
10
11 12 13
Total
Marks
1
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True/False & Multiple Choice Questions
Below are five true/false & three multiple-choice questions. Write the letter corresponding to the correct answer after “ANSWER”.
1) The Universe is infinite:
T) True
F) False
ANSWER to question 1:
(1 Mark)
2) Sunlight always travels with the speed c:
T) True
F) False
ANSWER to question 2:
(1 Mark)
3) Because the sky is dark at night, there is no radiation at night:
T) True
F) False
ANSWER to question 3:
(1 Mark)
4) Hooke’s law relates force to energy:
T) True
F) False
ANSWER to question 4:
(1 Mark)
5) Sound waves are transverse waves when traveling in a liquid:
T) True
F) False
ANSWER to question 5:
(1 Mark)
6) The dimension of a Parsec is:
A) m/s
C) kg m/s2
B) m
D) N m
ANSWER to question 6:
7) A mole of oxygen (atomic number 8) approximately contains:
A) 1 oxygen atom
B) 6 * 1023 oxygen atoms
D) 6 * 8 * 1023 oxygen atoms
C) 6/8 * 1023 oxygen atoms
ANSWER to question 7:
(1 Mark)
(1 Mark)
8) In the Doppler effect for light, a ‘blue shift’ means that the light source is:
A) Approaching
B) Receding
C) Stationary
D) Caused by sound waves
(1 Mark)
ANSWER to question 8:
END OF True/False & Multiple Choice Questions
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3
Fairly Short Questions
Below are four short questions. Write the answer after “ANSWER”.
9) We have a sound source at a distance of 10m from us with an intensity (at our ears)
of 100 decibels. The frequency of the source is 50Hz.
(i)
Due to effects of the sound source only, approximately, how far away does
a nitrogen atom located right in front of us move in 10 seconds?
(ii)
What is the wavelength of the sound wave?
ANSWERS to question 9:
(2 Marks)
10) We have a cubic container with a side of 0.1m filled with 2 moles of hydrogen gas
at room temperature (20 degrees Celsius).
(i)
What is the pressure in the container?
(ii)
If we add one mole of Oxygen and let it react with the Hydrogen, after
some long time (assuming that the container is still intact) will the pressure
be greater or smaller than in (i)? Explain your answer in no more than 3
short sentences.
ANSWERS to question 10:
(2 Marks)
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11) We know that a galaxy is receding with a speed of approximately 3 * 107m/s.
(i)
Approximately how far away is it in meters?
(ii)
Would it be sensible to specify the direction in the sky into which it is receding? Explain your answer in not more than 3 short sentences.
ANSWERS to question 11:
(2 Marks)
12) A diver is listening to music coming from a visible but fairly distant underwater
speaker. Suddenly, she sees someone pull the plug.
(i)
How long will it take until the diver stops hearing the music if the speaker
is about 3km away?
(ii)
What would happen in (i) if the speed of light in water were the same as the
speed of sound in water? Explain your answer in no more than 3 short sentences.
ANSWERS to question 12:
END of Fairly Short Questions
(2 Marks)
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Fairly Long Question
Below is a fairly long question. Write the answer where indicated in the question.
13) We are on top of a 100m high tower with our friend Frednotsoclever and would
like to investigate the laws of nature.
(i)
(ii)
(iii)
What is the potential energy of an iron ball with a mass of 1kg exactly at the
height of the tower?
If we drop the ball. What is the kinetic energy of the iron ball an infinitely
short time before hitting the ground?
Frednosoclever wants to determine the impact velocity by dividing the
height of the building by the time it takes to fall from the top to the bottom.
Of course this is wrong. How much will his calculation differ from the correct result?
ANSWERS to question 13:
More blank space on next page ….
(4 Marks)
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Blank space for your perusal.
END of Fairly Long Question
END OF TEST