Physical Science Exam 2

A 400-kg concrete block is 1 m long, 0.6 m wide, and 0.3 m high. Its density is rev: 11_06_2014_QC_58218,03_02_2015_QC_CS-8142 A. 2222 kg/m3 rev: 11_06_2014_QC_58218 B. 667 kg/m3 C. 222 kg/m3 D. 72 kg/m3

A. 2222 kg/m3 rev: 11_06_2014_QC_58218

The density of brass is 8 x 103 kg/m3. The volume occupied by 320 g of brass is A. 38 cm3 B. 0.038 cm3 C. 380 cm3 D. 3.2 cm 3

A. 38 cm3

The electric energy stored in a 6-V battery rated at 20 Ah is A. 432 kJ B. 120 J C. 12 kJ D. 7.2 kJ

A. 432 kJ

Which of the following statements is correct? A. Moving electrons constitute electric currents B. Electrons carry electric currents C. The motion of electrons produces electric currents D. Electric currents are carried by conductors and insulators only

A. Moving electrons constitute electric currents

A current-carrying wire is in a magnetic field with the direction of the current perpendicular to that of the field. A. The wire tends to move perpendicular to the field B. The wire tends to turn until it is perpendicular to the field C. The wire has no tendency to move or to turn D. The wire tends to move parallel to the field

A. The wire tends to move perpendicular to the field

Heat transfer in a vacuum A. can take place only by radiation B. can take place by radiation, convection, and conduction C. can take place only by radiation and convection D. cannot take place

A. can take place only by radiation

Heat transfer by conduction occurs A. in liquids, solids, and gases B. only in Solids C. only in liquids and solids D. only in Liquids

A. in liquids, solids, and gases

The physics of a heat engine cannot be used to understand the operation of a A. nuclear reactor B. diesel engine C. refrigerator D. heat pump

A. nuclear reactor

Superconductivity occurs in certain substances A. only at very low temperatures B. at all temperatures C. only when they are in the liquid state D. only at very high temperatures

A. only at very low temperatures

Heat transfer by convection occurs A. only in liquids and gases B. only in gases C. only in liquids D. in liquids, gases, and solids

A. only in liquids and gases

The volt is the unit of electric A. potential difference B. resistance C. current D. potential energy

A. potential difference

Two charges of +Q are 1 cm apart. If one of the charges is replaced by a charge of -Q, the magnitude of the force between them is A. the same B. larger C. zero D. smaller

A. the same

One liter of hydrogen gas at atmospheric pressure is allowed to expand to a volume of 3 liters w/ the temperature held constant. If the average speed of the hydrogen molecules was originally v, their new average speed is A. v B. 3v C. v/9 D. v/3

A. v

The specific heat of ice is 2.1 kJ/kg*C. When 50 kJ of heat is removed from 2 kg of ice initially at -5*C, the final temperature of the ice is A. -11*C B. -17*C C. -12*C D. -6*C

B. -17*C

The current in a 20-ohm electric heater operated at 240 V is A. 2880 A B. 12 A C. 4800 A D. 0.083 A

B. 12 A

A 400-kg concrete block is 1 m long, 0.6 m wide, and 0.3 m high. It can exert three different pressures on a horizontal surface, depending on which face it rests on. The highest pressure is A. 21.8 kPa B. 13.1 kPa C. 0.7 kPa D. 2.2 kPa

B. 13.1 kPa

In order to double the average energy of the molecules in a gas at 200 K, its temperature must be changed to A. 1600 K B. 400 K C. 100 K D. 800 K

B. 400 K

The power rating of an electric motor that draws a current of 3 A when operated at 240 V is A. 1080 W B. 720 W C. 2160 W D. 80 W

B. 720 W

WHich of the following formulas relating temperatures on the Celsius and Fahrenheit scales is correct? A. Tc= (9/5)(TF+32*) B. Tc=(5/9)(TF-32*) C. Tc=(5/9)(TF=32*) D. Tc=(9/5)TF-32*)

B. Tc=(5/9)(TF-32*)

A thermometer calibrated in the Celsius scale and a thermometer calibrated in the Fahrenheit scale are used to measure the same temperature. The numerical reading on the Fahrenheit thermometer A. is smaller than that on the Celsius thermometer B. may be smaller or larger than that on the Celsius thermometer C. is proportional to that on the Celsius thermometer D. is larger than that on the Celsius thermometer

B. may be smaller or larger than that on the Celsius thermometer

A sample of a gas is expanded to twice its original volume while its temperature is held constant. Relative to their original average energy, the new average energy of the molecules is A. twice as great B. the same C. four times as great D. half as great

B. the same

If undisturbed, an electric current in a superconducting wire loop A. will decrease to a stop in a day or two B. will continue indefinitely C. will gradually increase D. will decrease to a stop in a few seconds

B. will continue indefinitely

An absolute temperature of 100 K is the same as a Celsius temperature of A. 32*C B. 373*C C. -173*C D. 212*C

C. -173*C

Molecular motion in a gas is the minimum possible at A. -273 K B. 0*C C. 0 K D. 0*F

C. 0 K

An ideal frictionless engine takes in 10 kJ of heat per second when it operates between 500 K and 400 K. The work that engine does per second is A. 8 kJ B. 10 kJ C. 2 kJ D. 2.5 kJ

C. 2 kJ

A typical metabolic rate while walking is A. 1.2 kW B. 50 W C. 300 W D. 10 W

C. 300 W

The specific heat of water is 4.2 kJ/kg*C. How long will it take for a 2-kW heating element to raise the temperature of 30 kg of water from 20*C to 80*C? A. 15 min B. 6.3 min C. 84 min D. 63 min

C. 84 min

In order to operate, a heat engine must have A. either a hot or a cold reservoir B. a supply of fuel that can be burned, such as coal or oil C. both a hot and a cold reservoir D. a boiler

C. both a hot and a cold reservoir

Radiation is emitted A. only by solids B. only by liquids and solids C. by liquids, solids and, gases D. only by liquids

C. by liquids, solids and, gases

The entropy of a system is a measure of its A. temperature B. density C. disorder D. heat content

C. disorder

An object has a positive charge whenever A. the nuclei of its atoms are positively charged B. it has an excess of electrons C. it has a deficiency of electrons D. the electrons of its atoms are positively charged

C. it has a deficiency of electrons

The temperature of a gas sample in a rigid container is reduced. The pressure the gas exerts on the container walls decreases because A. its molecules are in contact with the walls for briefer intervals B. its molecules lose less energy each time they strike the walls C. its molecules have lower average speeds and so strike the walls less often with less momentum D. its molecular masses decrease

C. its molecules have lower average speeds and so strike the walls less often with less momentum

A cake of soap is placed in a bathtub sink. The buoyant force on the soap is A. equal to its weight B. more than its weight C. less than its weight D. 0

C. less than its weight

Electric charge A. occurs only in separate parcels whose value depends on the particle carrying the charge B. occurs only in separate parcels of +/- 1 C C. occurs only in separate parcels of +/- 1.6 x 10 -19 C D. can be subdivided indefinitely

C. occurs only in separate parcels of +/- 1.6 x 10 -19 C

A refrigerator A. produces cold B. causes heat to disappear C. removes heat from a region and carries it elsewhere D. changes heat to cold

C. removes heat from a region and carries it elsewhere

When a gas is forced into a smaller volume without a change in temperature, its pressure increases because its molecules A. strike the container walls with greater force B. have more energy C. strike the container walls more often D. strike the container walls at higher speeds

C. strike the container walls more often

The melting point of water is 0*C. Its freezing point is A. slightly less than 0*C B. 32*C C. slightly more than 0*C D. 0*C

D. 0*C

If it is to be 40 percent efficient, a heat engine that exhausts heat at 350 K must absorb heat at a minimum temperature of A. 1038 K B. 210 K C. 875 K D. 583 K

D. 583 K

Ethanol boils at 172*F. The Celsius equivalent of this temperature is A. 140*C B. 278*C C. 64*C D. 78*C

D. 78*C

A magnet does not exert a force on A. a moving electric charge B. a magnetized iron bar C. an magnetized iron bar D. a stationary electric charge

D. a stationary electric charge

A barometer measures A. water density B. water pressure C. atmospheric density D. atmospheric pressure

D. atmospheric pressure

A drawing of the field lines of a magnetic field provides information on A. the strength of the field only B. the source of the field C. the direction of the field only D. both the direction and the strength of the field

D. both the direction and the strength of the field

In an isolated system, entropy A. may increase, decrease, or remain constant B. cannot increase C. must remain constant D. cannot decrease

D. cannot decrease

A molecule that has lost an electron becomes a A. positive ion B. negative ion C. superconductor D. electric charge

D. electric charge

The conventional unit of battery capacity is the ampere-hour, which is actually a unit of A. power B. energy C. potential difference D. electric charge

D. electric charge

Molecules are, in general, farthest apart from one another in A. amorphous solids B. crystalline solids C. liquids D. gases

D. gases

Steam at 100*C is more dangerous than the same mass of water at 100*C because the steam A. moves faster B. had a higher specific heat C. is less dense D. releases a great deal of heat when it condenses

D. releases a great deal of heat when it condenses

Sublimation refers to A. the condensation of a gas into a liquid B. the melting of a solid C. the vaporization of a liquid D. the vaporization of a solid without first becoming a liquid

D. the vaporization of a solid without first becoming a liquid

Direct electric current cannot be used to operate A. electromagnets B. electric motors C. electric heaters D. transformers

D. transformers

The average pressure of the atmosphere at sea level corresponds to which one or more of the following? A. 101 Pa B. 15 lb/in2 C. 98 kPa D. 101 kPa E. Both B and D

E. Both B and D: 15 lb/in2, 101 kPa