Short Answers Conceptual Questions
1. (a) A lead cylinder floats in mercury at 0oC. Will the lead
float higher or lower if the temperature is raised? (b) Freezing a
can of soda will cause its bottom and top to bulge so badly that
the can will not stand up. What has happened?
2. (a) Is it possible to boil water at room temperature (20oC)
without heating it? Explain. (b) Explain why burns caused by steam
at 100oC on the skin are often more severe than burns caused by
water at 100oC?
3. (a) Distinguish between the concepts of thermal energy,
temperature, and heat. (b) Write a short paragraph explaining why
fish live through cold winters even when the ponds are frozen
over.
4. (a) Write a short paragraph distinguishing between
conduction and convection. Give two examples of each. (b) From a
molecular point of view, explain why evaporation is a cooling
process. What cools?
5. (a) Distinguish between a transverse wave and a
longitudinal wave. Give examples of each. (b) What is wave
interference, and the two types of wave interference?
6. (a) What kind of waves do you think will travel down a
horizontal metal rod if you strike its end (i) vertically from
above (ii) horizontally parallel to its length? (b) A tire swing
hanging from a branch reaches nearly to the ground (as shown
below). How could you estimate the height of the branch using only
a stopwatch?
7. (a) Describe how you could estimate the speed of water
waves across the surface of a pond. (b) What evidence can you give
that the speed of sound in air does not depend significantly on
frequency?
Think and Rank
8. (a) Rank the magnitudes of these units of thermal energy
from greatest to least: (i) 1 calorie, (ii) 1 Calorie, (iii) 1
joule. (b) From greatest to least, rank the energy needed for these
phase changes for equal amounts of H2O: (i) from ice to ice water,
(ii) from ice water to boiling water, and (iii) from boiling water
to steam.
9. (a) Rank the speed of sound in through the following media
from fastest to slowest: (i) air, (ii) steel, (iii) water. (b) All
the waves shown in Fig. 1 below have the same speed in the same
medium. Use a ruler and rank these waves from greatest to least
for: (i) amplitude, (ii) wavelength, (iii) frequency, and (iv)
period.
Fig. 1
Problems
10. (a) A volume of helium gas has a temperature of 10°C. The
same gas twice as hot has a temperature of
A) 10°C. B) 12°C. C) 283°C. D) 293°C. E) none of the
above
10. (b) What would be the temperature of 50 g of 20°C water
mixed with 80 g of 40°C water?
A) 24.6°C B) 26.9°C C) 27.6°C D) 28.3°C E) 32.3°C
11. (a) As a train of water waves goes by, a piece of cork
floating on the water bobs up and down one complete cycle each
second. The waves are 2 m long. What is the speed of the
wave?
A) 0.25 m/s B) 0.50 m/s C) 1.0 m/s D) 2 m/s E) 4 m/s
11. (b) The range of human hearing is about
A) 10 Hz - 10,000 Hz. B) 20 Hz - 20,000 Hz. C) 40 Hz - 40,000
Hz.
D) all of the above, depending on the person
12. (a) Suppose you sound a 1056-Hz tuning fork when you
strike a note on the piano and hear 2 beats/second. You tighten the
piano string very slightly and now hear 3 beats/second. What is the
frequency of the piano string?
A) 1053 Hz B) 1054 Hz C) 1056 Hz D) 1058 Hz E) 1059 Hz
12. (b) The fundamental frequency of a violin string is 440
Hz. The frequency of its second harmonic is
A) 220 Hz. B) 440 Hz. C) 880 Hz.