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Physics 102 Exam 1
20 February 2002 Prof L. Weinstein
Please give a short explanation for all of your non-numerical answers (unless otherwise noted). Show your work for all numerical answers.

Useful numbers: Atmospheric pressure = $10^5$ Pa = 100,000 N/m$^2$

Absolute zero = 0 K = -273$^o$ C = -459$^o$ F

  1. (No explanation needed.) Which of the following are electrically neutral (circle as many as apply)?
    1. proton
    2. neutron
    3. electron
    4. none of these
  2. (No explanation needed.) What makes an element distinct?
    1. the number of protons
    2. the number of electrons
    3. the number of neutrons
    4. the total number of protons and neutrons
    5. other
  3. (No explanation needed.) A dam is thicker at the bottom than the top partly because
    1. water is denser at deeper levels
    2. water pressure increases with depth
    3. surface tension exists only on the surface of liquids
    4. it looks better
    5. none of these
  4. (No explanation needed.) A one-ton blimp hovers in the air. The buoyant force acting on it is
    1. zero
    2. less than one ton
    3. one ton
    4. more than one ton
    5. need more information

     
     
     
     
     
  5. (No explanation needed.) Objects that radiate well, also
    1. absorb radiation well
    2. reflect radiation well
    3. both
    4. neither
  6. (No explanation needed.) Compared to the atoms in a newborn baby, the atoms in the body of an elderly person are
    1. newer
    2. older
    3. the same age
  7. The volume of matter comes mostly from its
    1. protons and neutrons
    2. electrons
    3. other

     
     
     
     
     
  8. The buoyant force on a rock is least when the rock is completely submerged and
    1. near the surface
    2. near the bottom
    3. halfway to the bottom
    4. they're all the same

     
     
     
     
     
  9. In class I demonstrated Magdeburg Spheres that could not be pulled apart when there was a vacuum inside. They have a surface area of about 30 in$^2$ = 0.020 m$^2$. What is the force on the Magdeburg Spheres from atmospheric pressure? How does this compare to the force that you can exert?

    10.  

     
     
     
     
     
     
     

  10. A beaker is filled half-full with water and placed on a scale to measure its weight. You lower a wooden rod partway into the water (without letting go) so that it does not touch the sides or bottom of the beaker. The apparent weight of the beaker (as measured by the scale)
    1. increases
    2. decreases
    3. remains the same
    4. depends on the size and density of the rod
    5. need more information

     
     
     
     
     
  11. A large motorboat loaded with a barrel of water floats in a swimming pool. If the water in the barrel is poured overboard (into the pool), the water level in the pool will
    1. rise
    2. fall
    3. remain unchanged
    4. need more information

     
     
     
     
     
  12. From how deep a hole can water be theoretically lifted by a vacuum pump at sea level?
    1. Less than 10 m deep
    2. about 10 m deep
    3. as deep as you want, just suck harder
    4. need more information

     
     
     
     
     
  13. When a gas in a container is squeezed to half its volume (at constant temperature), its pressure
    1. quarters
    2. halves
    3. stays the same
    4. doubles
    5. quadruples

     
     
     
     
     
  14. During a very cold winter, water pipes sometimes burst. Why does this happen?

    15.  

     
     
     
     
     
     
     

  15. An umbrella tends to move upwards on a windy day principally because
    1. air gets trapped under the umbrella, warms, and rises
    2. buoyancy increases with increasing wind speed
    3. air pressure is reduced over the curved top surface
    4. all of these
    5. other

     
     
     
     
     
  16. Heat an iron plate with a small hole in it. The hole
    1. gets bigger
    2. gets smaller
    3. remains the same size

     
     
     
     
     
  17. Aluminum has a specific heat capacity more than twice that of copper. Add equal amounts of heat to equal masses of aluminum and copper. Which will increase in temperature faster?
    1. the aluminum
    2. the copper
    3. both the same

     
     
     
     
     
  18. A can of air is sealed at atmospheric pressure and room temperature (20$^o$ C or 70$^o$ F). To double the pressure in the can, you must heat it to
    1. 40$^o$ C
    2. 140$^o$ F
    3. 273$^o$ C
    4. 313$^o$ C
    5. 586$^o$ C

     
     
     
     
     
  19. A pot of clean snow and a pot of dirty snow are placed in the sunlight. The snow to melt first will be the
    1. clean snow
    2. dirty snow
    3. both the same
    4. need more information

     
     
     
     
     
  20. The planet Earth loses heat mainly by
    1. conduction
    2. radiation
    3. convection
    4. all of these
    5. none of these

     
     
     
     
     
     
     

 
2002-03-08