Test 2
Fall 1997
PART I: True and False answers. (2 points each, Total of 42 points):
(Note: The answer to Part I is given at the end)

1. A molecule is the smallest particle that exists.

2. There are thousands of different kinds of atoms that account for a wide variety of substances.

3. The kinetic energy of a satellite moving in an elliptical orbit is always constant.

4. The gravitational constant G is a universal constant.

5. If the radius of the earth somehow decreased with no change in mass, your weight would increase.

6. When a star collapses to form a black hole, its mass decreases.

7. The Pascal is a pressure unit equal to one Newton per square meter.

8. One calorie is the amount of heat required to change the temperature of 1 kg of water by 1 degree Celsius.

9. On the Celsius temperature scale, the interval between the ice and steam points is divided into 100 equal degrees.

10. Atmospheric pressure is caused by the temperature of the atmosphere.

11. As a Helium-filled balloon rises in the air, it becomes more dense.

12. The faster a fluid moves, the lesser its internal pressure.

13. When gas in a container is squeezed to half its volume, its density halves.

14. Hooke's law states that the amount of stretch or compression of an elastic material is inversely proportional to the applied force.

15. A substance that heats up relatively quickly has a high specific heat.

16. According to Newton, doubling the distance between two interacting objects divides by 2 the gravitational force between them.

17. In oceans heat flows from the North pole to the equator.

18. The density of one kilogram of water is greater than the density of one gram of water.

19. Silver warms up faster than iron when heat is applied therefore iron cools faster when heat is removed.

20. No heat could be transferred from ice because its temperature is 0 °C.

21. The cube of the times of revolutions of the planets are proportional to the squares of their average distances form the sun.

Answer ( Part I ) True Answers:4, 5, 7, 9, 12 False Answers: remaining questions

PART II: Multiple Choice Questions. (2 points each, Total of 42 points):

1. According to Kepler's laws, the paths of planets about the sun are
a. parabolas
b. circles
c. straight lines
d. ellipses
Answer d

2. A black hole is
a. an empty region of space with a huge gravitational field.
b. a small region that contains the mass of many galaxies.
c. simply the remains of a giant star that has undergone gravitational collapse.
d. none of the above.
Answer c

3. Brownian motion has to do with the
a. random motions of atoms and molecules.
b. chemical reactions.
c. size of atoms.
d. all of these.
e. none of these.
Answer a

4. The specific heat of substance A is ten times greater than that of substance B. If equal amounts of heat are added to equal masses of A and B, the temperature increase of substance A is
a. the same as that of B
b. ten times greater than that of B
c. 1/10 that of B
d. none of the preceding
Answer c

5. The force of gravity changes the speed of a satellite in
a. circular orbit.
b. elliptical orbit.
c. both of these.
d. neither of these.
Answer b

6. Compared to the atoms that make up the body of an old person, the atoms that make up the body of a newborn baby are
a. newer
b. actually older
c. the same age
Answer c

7. Which of the following are electrically neutral?
a. proton.
b. neutron.
c. electron.
d. all of these.
Answer b

8. The air in this room has
a. mass.
b. weight.
c. energy.
d. all of these.
e. none of these.
Answer d

9. Compared to the period of satellites in orbit close to the earth, the period of satellites in orbit far from the earth is
a. longer.
b. shorter.
c. the same.
d. not enough information.
Answer a

10. Temperature is
a. a measure of heat
b. a relative measure of hotness and coldness
c. both (a) and (b)
Answer b

11. Heat is
a. a form of energy
b. energy transferred because of a temperature difference
c. both (a) and (b)
Answer c

12. Planets would crash into the sun if it weren't for
a. their tangential velocities.
b. their vast distances from the sun.
c. the inverse-square law.
d. their relatively small masses.
Answer a

13. Heat energy is measured in units of
a. joules.
b. calories.
c. Calories.
d. all of these.
Answer d

14. The lowest possible temperature is
a. 273 °C
b. the absolute zero
c. 0 °F
d. 273 K
Answer b

15. A dam is thicker at the bottom than at the top because
a. water is denser at deeper levels.
b. water pressure is greater with increasing depth.
c. surface tension exists only on the surface of liquids.
d. none of these.
Answer b

16. The reason that buoyant force acts upward on a submerged object is that
a. it acts in a direction to oppose gravity.
b. if it acted downward, nothing would float.
c. the weight of fluid displaced reacts with an upward force.
d. upward pressure against the bottom is greater than downward pressure against the top of the submerged object.
Answer d

17. A plasma, the so called fourth phase of matter, is
a. a combination of a solid and a liquid.
b. a gas dissolved in a liquid.
c. a combination of the other three phases of matter.
d. a gaseous mixture of electrons and ions.
Answer d

18. 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 tones.
d. 100 m3
e. depends on the ship's shape.
Answer b

19. Water will float on Mercury because
a. Mercury has greater surface tension
b. Water is denser than Mercury
c. the atmospheric pressure is 760 mmHg
d. none of the above
Answer d

20. Heat energy travels from an object with a high
a. internal energy to an object with a lower internal energy.
b. temperature to an object with a lower temperature.
c. both of these.
Answer b

21. Consider two planets in space that gravitationally attract each other. If the masses of both planets are doubled, and the distance between them is also doubled, then the force between them is
a. one quarter.
b. half as much.
c. twice as much.
d. four time as much.
e. none of these.
Answer e

PART III: Fill-In the Blanks (1 point for each blank, a total of 15 points) :

1. Consider a balloon filled with 3 liter of water (1 liter = 1000 cm³ ) in equilibrium in a container.
a. what is the mass of 3 liters of water?................................................
b. What is the weight of the balloon of water?................................................
c. What is the weight of water displaced by the balloon?................................................
d. What is the buoyant force on the balloon?..........................................
Answer a) 3 kg b) 30 N c) 30 N d) 30 N

2. Consider a cube 1 cm x 1 cm x 1 cm. Its volume is 1 cm³. The surface area of one of its faces is 1 cm². The total surface area of the cube is 6 cm². Now consider a second cube, scaled up by a factor of 2 so it is 2 cm x 2 cm x 2 cm.
a. What is the total surface area of the second cube?................................................
b. What is the volume of the second cube?................................................
c. What is the ratio of surface area to volume for the first cube?...........................................
d What is the ratio of surface area to volume for the second cube?..................................

Answer a) 2*2*6 = 24 cm**2 b) 2*2*2 = 8 cm**3 c) 6cm**2/1cm**3 = 6cm**(-1) c) 24cm**2/8cm**3 = 3cm**(-1)

3. If we go twice as deep in a lake the pressure will be .......................................... times greater.

Answer two

4.

The kinetic energy is maximum at point ............
The potential energy is maximum at point............
The magnitude of the acceleration at point ............ and point ............is the same
The speed is minimum at point ............

Answer A C B, D C

5. When the distance between two objects is halved the gravitational force between them is increases by .........................times.

Answer four