Test 2
Spring 1998
PART I: True and False questions. (2 points each, Total of 44 points):
(Note: The answer to Part I is given at the end)
1. Drinking through a straw is more difficult in Ifrane (high altitude) than in Rabat (low altitude).
2. Nearly all the mass of an atom is concentrated in its nucleus.
3. When carbon and oxygen atoms combine, energy is given off.
4. In water, immersed objects are buoyed upward, but in air they are buoyed downward.
5. Water speeds up when it flows from a large pipe into a narrower pipe therefore the internal pressure of water is higher in the narrower pipe.
6. While you're taking the test, there is a buoyant force acting on you, and you're buoyed upward by it.
7. All substances can be transformed from any phase to another.
8. A floating object always displaces a volume of liquid equal to its own volume.
9. If an object is less dense than the fluid in which it is immersed, it will sink.
10. What makes one element distinct from another is the number of total particles in its nucleus.
11. Atmospheric pressure is caused by the weight of air.
12. Iron warms up faster than glass when heated.
13. When an iron ring is heated, the hole becomes smaller.
14. An adiabatic process is characterized by the absence of heat exchange.
15. A good heat conductor is a good insulator.
16. Hot water will cool to room temperature faster in a silver pot than a black pot.
17. The planet Earth loses heat mainly by conduction.
18. For increased atmospheric pressure, the boiling temperature of a liquid goes down..
19. The food in the refrigerator is cooled by condensation of the refrigerating fluid.
20. Food cooked in boiling water in the mountains cooks faster than when cooked at sea level.
21. It is possible to totally convert a given amount of mechanical energy into heat.
22. As a blob (large mass of air) at a high elevation sinks to a lower elevation with no heat input or output, its temperature decreases.
PART II: Multiple Choice Questions. (2 points each, Total of 44 points):
1. Water is
a. an element
b. a compound
c. a mixture
d. all of the above
e. none of the above
2. In the atomic nucleus of a certain element there are 26 protons and 28 neutrons. The ATOMIC NUMBER of the element is
a. 26
b. 27
c. 28
d. 54
e. none of these
3. A helium-filled elastic balloon rises in the air. The helium inside the balloon becomes
a. lighter
b. less dense
c. all of these
d. none of these
4. The density of 100 kg of water is
a. 1 kg/m^3
b. 10 kg/m^3
c. 100 kg/m^3
d. 1000 kg/m^3
5. In a windy day, atmospheric pressure
a. increases
b. decreases
c. does not change
6. Three identical bowling balls are suspended at various depths in water as shown. Buoyant force is greater on ball
a. A
b. B
c. C
d. same on each
7. What is the mass of water displaced by a 100-ton floating ship?
a. less than 100 tons
b. 100 tons
c. more than 100 tons
d. 100 cubic meters
e. depends on the ship's shape
8. A metal has a mass of 5 grams and a volume of 1 cm^3. A piece of the same kind of metal with a volume of 2 cm^3 has a density of
a. 2.5 g/cm^3
b. 5 g/cm^3
c. 10 g/cm^3
9. A molecule has
a. mass
b. structure
c. energy
d. all of these
e. none of these
10. The reason a life jacket helps you float
a. the jacket makes you weigh less.
b. the jacket has the same density as an average human
c. the jacket repels water
d. if you sink, the jacket sinks
e. the density of both you and the jacket is less than your density alone.
11. As a balloon rises higher and higher into the atmosphere, its
a. volume decreases
b. density increases
c. weight increases
d. mass decreases
e. none of these
12. When you touch a cold piece of ice with your finger, energy flows
a. from your finger to the ice.
b. from the ice to your finger.
c. actually, both ways.
13. Heat energy is measured in units of
a. joules.
b. calories.
c. both of these.
14. Systems that are left alone, tend to move toward a state of
a- less entropy.
b- more entropy.
c- no entropy.
15. A substance can absorb heat energy by the process of
a. conduction.
b. convection.
c. radiation.
d. all of these.
16. Energy transfer by convection is primarily restricted to
a. solids.
b. liquids.
c. gases.
d. fluids.
e. none of these.
17. Objects that radiate relatively well,
a. absorb radiation relatively well.
b. reflect radiation relatively well.
c. both of these.
d. neither of these.
18. We feel uncomfortably warm on a muggy (humid) day because water molecules are
a. evaporating from our moist bodies.
b. condensing on our bodies.
c. preventing the evaporation from our moist bodies.
19. When a gas is changed to a liquid state, the gas
a. releases energy.
b. absorbs energy.
c. neither releases nor absorbs energy.
20. When a solid is changed to a liquid state, the solid
a- releases energy.
b- absorbs energy.
c- neither releases nor absorbs energy.
21. The lowest temperature possible in nature is
a- 0 degrees C.
b- -273 degrees C.
c- 4 K.
d. -400 degrees C
22. The first law of thermodynamics is a restatement of the
a- principle of entropy.
b- law of heat addition.
c- Carnot cycle.
d- conservation of energy
e. none of these.
PART III: Fill-In the Blanks (2 point for each blank, a total of 10 points)
:
1. The minimum amount of energy required to melt 5 grams of 0-degree-C ice is ............
2. One hundred joules of heat is added to a system that performs 60 joules of work. The internal energy change of the system is ...................
3. The ideal efficiency for a heat engine operating between temperatures of 2700 K and 300 K is ....................
4. A hydrogen-filled balloon that weighs 20N must displace ..........N of air in order to float in air.
5. If a force of 5 N stretches a certain spring 4 cm how much stretch will occur for an applied force of 15 N? .....................