SAT II Physics (Gary Graff) Episode 2 Part 6 potx

B The force the ball exerted on the window was smaller than the force the window exerted on the ball?. E The kinetic energy the ball had before it broke the window equaled the kinetic en

PHYSICS PHYSICS TEST—TEST—TEST—Contin Contin Continued ued

61 The most notable difference between a

radio wave and a light wave is

62 Which of the graphs above shows two

electrons as they separate from one

of collision represented in this example is(A) an elastic collision

(B) a perfectly inelastic collision

(C) an inelastic collision

(D) all of the above

(E) none of the above

64 The images formed by convex mirrors(A) are always real

(B) are always virtual

(C) are only real when the object is placedoutside the radius of curvature

(D) are only virtual when the object isplaced inside the focal point

(E) None of the above describes theimages formed by convex mirrors

65 Two different light bulbs are in a DC

circuit powered by an 18 V battery as its

power source The two bulbs are rated at

4.5 watts (B1) and 6.75 watts (B2) each.What are the resistances of the two light

PHYSICS PHYSICS TEST—TEST—TEST—Contin Contin Continued ued

67 The volt is a measure of electrical potential

and may be defined as

(A) opposition to electrical motion

(B) number of particles in motion

(C) work per unit charge

(D) field strength per unit of force

(E) electrostatic discharge

68 A laboratory centrifuge starts from rest and

reaches a rotational speed of 8,000

radi-ans/sec in a time of 25 seconds What is the

angular acceleration of the centrifuge?

69 An object at rest is placed into free fall at a

height of 20 m What is the velocity of the

object when the PE equals the KE?

(A) 8 m/s

(B) 11 m/s

(C) 14 m/s

(D) 17 m/s

(E) Velocity cannot be determined

70 A battery and a variable resistor are inseries with a small fan A switch is closed,and the fan runs When the variable resis-tor is moved slightly to the left, the fanslows down a little When the variableresistor is moved slightly to the right, thefan speeds up a little The following ques-tion is about the operation of the circuitdescribed If the variable resistor in thecircuit is set all the way to the right, whathappens in the circuit?

I The fan runs faster

II The voltage decreases

III The current increases

(A) I only(B) II only(C) I and III only(D) II and III only(E) I, II, and III

PRACTICE TEST 3

PHYSICS PHYSICS TEST—TEST—TEST—Contin Contin Continued ued

71 A pulse on a string moves toward and

strikes a fixed end as shown The pulse is

(A) reflected and transmitted

(B) reflected and refracted

(C) reflected and reduced

(D) reflected and magnified

(E) reflected and inverted

72 A thrown baseball hits and breaks a glass

window and ends up inside the house

Which of the following is correct about the

ball?

(A) The force the ball exerted on the

window was larger than the force the

window exerted on the ball

(B) The force the ball exerted on the

window was smaller than the force

the window exerted on the ball

(C) The force the ball exerted on the

window was the same as the force the

window exerted on the ball

(D) Since the ball broke the window, it

didn’t lose any momentum

(E) The kinetic energy the ball had before

it broke the window equaled the

kinetic energy the ball had after it

broke the window

PHYSICS TEST

73 When a voltage source that is inducingvoltage into a large number of coils isdisconnected, and a switch that is in serieswith the coils of wire is also opened, aspark is observed to jump across theswitch terminals as the switch begins toopen up What is the cause of this spark?(A) Free electrons from the voltage source(B) Free electrons from the coils of wire(C) Collapse of the magnetic field in thecoils of wire

(D) Secondary electron flow from thesource

(E) Stored voltage in the coils of wire

74 Electrical energy is changed into cal energy in a device called a/an

PHYSICS PHYSICS TEST—TEST—TEST—Contin Contin Continued ued

75 Two wires are aligned side by side as

shown above They are both hooked into

different circuits in which the current is off

A switch is closed, allowing current to flow

into each circuit Which of the following

statements is correct?

(A) The two currents destructively

inter-fere with one another

(B) The two currents constructively

interfere with one another

(C) The two wires attract and move

closer

(D) The two wires repel and move away

(E) The two wires remain still

PRACTICE TEST 3

ANSWER SHEET

Leave any unused

answer spaces blank.

PRACTICE TEST 3

ANSWERS ANSWERS AND EXPLAN AND EXPLAN AND EXPLANA A ATIONS TIONS

ANSWERS AND EXPLANATIONS

ANSWERS TO PART A, QUESTIONS 1–14

1

1 The corThe corThe corrrrrrect ansect ansect answwwer is (B)er is (B)er is (B) The velocity of the object is constantbetween the 3rd and 4th seconds An acceleration is defined asthe time rate change in velocity, a v

2 The corThe corThe corrrrrrect ansect ansect answwwer is (E).er is (E).er is (E) The magnitude of the acceleration is

greatest between t = 10s and t = 11s The slope of the graph is

steeper between these two times than anywhere else on thegraph

6

6 The corThe corThe corrrrrrect ansect ansect answwwer is (A)er is (A)er is (A) The voltage measurement out the circuit decreases as the distance from point A increasesand the number of resistors the current has passed throughincreases Each increase in the resistance produces a corre-sponding decrease in voltage

7

7 The corThe corThe corrrrrrect ansect ansect answwwer is (C)er is (C)er is (C) The part of the cycle represented bythe letter C is compression During compression, the systemheat is kept constant by allowing heat to escape from the sys-tem

8

8 The corThe corThe corrrrrrect ansect ansect answwwer is (E)er is (E)er is (E) The work done by a heat engine isthe area under the pressure-volume curve The work done underthe A part of the diagram is positive work, but the negative workdone under the C part of the diagram must be subtracted, leav-ing the work as E

9

9 The corThe corThe corrrrrrect ansect ansect answwwer is (A)er is (A)er is (A) The volume of the enclosed gasincreases during phase A

PRACTICE TEST 3

10 The corThe corThe corrrrrrect ansect ansect answwwer is (D)er is (D)er is (D) As long as the object is moving, thefrictional force is a constant force that opposes motion This isshown in graph D

11

11 The corThe corThe corrrrrrect ansect ansect answwwer is (C)er is (C)er is (C) The object is subjected to a constantnegative acceleration (it is slowing down) The velocity timegraph for an object that is subjected to a constant acceleration is

a linear curve, as in the graph shown in C

12

12 The corThe corThe corrrrrrect ansect ansect answwwer is (A)er is (A)er is (A) The object increases its ment from the origin until it stops moving Then the objectremains in its position where its motion ceased

displace-13

13 The corThe corThe corrrrrrect ansect ansect answwwer is (A)er is (A)er is (A) The parent nucleus is the nucleuswith which the nuclear reaction begins In this case 235

92U is theparent nucleus

14

14 The corThe corThe corrrrrrect ansect ansect answwwer is (B)er is (B)er is (B) An alpha particle is a heliumnucleus That is, it is 4

2He.15

15 The corThe corThe corrrrrrect ansect ansect answwwer is (D)er is (D)er is (D) The beta particle is a high-energyelectron It has the symbol 0

1

− e, or β .

ANSWERS AND EXPLANATIONS

ANSWERS TO PART B, QUESTIONS 16–75

16

16 The corThe corThe corrrrrrect ansect ansect answwwer is (E)er is (E)er is (E) All of the choicesexhibit a wave nature at some time All waves caninterfere with one another, either constructively ordestructively

17

17 The correct answer is (D)The correct answer is (D)The correct answer is (D) Objects that aretouched by the charging body are charged by

18 The corThe corThe corrrrrrect ansect ansect answwwer is (E).er is (E).er is (E) The force the particles exert on oneanother increases as the inverse of the square of the distancebetween the two particles

19

19 The corThe corThe corrrrrrect ansect ansect answwwer is (A)er is (A)er is (A) The higher the frequency of the lightwaves, the higher the energy of the photons Of the choicespresented, blue light has the highest frequency

20

20 The corThe corThe corrrrrrect ansect ansect answwwer is (D)er is (D)er is (D) The acceleration affects the spider

in the same way that it affects the observer If the elevator were

in free fall, everything in the elevator would free fall together,including the spider If the elevator accelerates upward, thespider experiences an apparent gain in weight, just as a personriding in the elevator does

21

21 The corThe corThe corrrrrrect ansect ansect answwwer is (B)er is (B)er is (B) When water freezes, it becomes lessdense Therefore, when ice cubes are placed into liquid water,they displace a volume of water equal to their weight When theice melts no further, volume is added to the container

V

V = , or 1:5

24

24 The corThe corThe corrrrrrect ansect ansect answwwer is (B)er is (B)er is (B) The equilibrant vector is pointed

into the third quadrant The y component for a vector in the

third quadrant also points into the third quadrant

25

25 The correct answer is (A)The correct answer is (A)The correct answer is (A) Gravity has nothing to do with heattransfer Both objects will reach the same temperature whenthey have reached equilibrium

26

26 The corThe corThe corrrrrrect ansect ansect answwwer is (D)er is (D)er is (D) The image produced when theobject is placed inside the focal distance of a convex mirror isvirtual and reduced

PRACTICE TEST 3

27 The correct answer is (B)The correct answer is (B)The correct answer is (B) Since the centripetal force is found

with the equation F m v

r

c =( )( 2) we can change the r value to 5r

and substitute it into the equation and solve to find the relative

force F m v

r

c =( )( )

2

5 Clearly the force will be double when the

radius is halved and the velocity remains the same

28

28 The corThe corThe corrrrrrect ansect ansect answwwer is (C)er is (C)er is (C) The heat added to the system minusthe work done by the system yields the heat that is exhaustedbetween points CD

29

29 The corThe corThe corrrrrrect ansect ansect answwwer is (A)er is (A)er is (A) The definition of the frequency of awave system is the number of waves per unit time, which is thesame as saying the number of crests that pass a given point over

a given time

30

30 The corThe corThe corrrrrrect ansect ansect answwwer is (C)er is (C)er is (C) The centripetal acceleration is found

with the following equation: v

r

2

=(2.5m/s) =.22m 28.4m/s

the substance by 1°C If substance A has a specific heat capacity

that is twice the specific heat capacity of substance B, that meanstwice as much heat is required to raise the temperature of

substance A as is required for substance B The converse is alsotrue—the heat required to raise the temperature of substance A

by 1°C will raise the temperature of substance B by 2°C.

32

32 The correct answer is (A)The correct answer is (A)The correct answer is (A) Centripetal force is also called thecenter-seeking force Both the tire and the golf ball roll abouttheir centers of mass, which are located in the center of theobjects The centripetal force for the two cannot be equalbecause the radii of the two objects are different, yet they rollwith the same tangential velocity

ANSWERS AND EXPLANATIONS

is also equal to half the weight of the block (F f= F11 ), so thetension in the rope is equal to the sum of the two forces, which

is equal to the weight of the block

34

34 The corThe corThe corrrrrrect ansect ansect answwwer is (C)er is (C)er is (C) The closer a satellite orbits theearth, the faster its period of rotation The farther a satelliteorbits from the earth, the longer its period of rotation

35

35 The corThe corThe corrrrrrect ansect ansect answwwer is (E).er is (E).er is (E) Look at the graph of velocity It is astraight line The velocity increases by the same amount each

second, additional proof that V = at.

Time Acceleration Velocity Increase

1 sec 9.8 m/s2 9.8 m/s +9.8m/ss

2 sec 9.8 m/s 19.6 m/s +9.8m/s

3 sec 9.8 m/s 29.4 m/s +9.8m/s

2 2

37

37 The corThe corThe corrrrrrect ansect ansect answwwer is (E)er is (E)er is (E) All of the methods listed cause thewire to move through the magnetic field or lines of force, whichinduces a voltage into the wire

38

38 The correct answer is (C)The correct answer is (C)The correct answer is (C) Scientists look at the light from astar by passing the light through a spectometer, which separatesthe starlight into the individual line spectra of the elements thatare burning in the star

41

41 The corThe corThe corrrrrrect ansect ansect answwwer is (B)er is (B)er is (B) When a light ray enters an opticallydenser material, it bends toward the normal because the lightslows down in the material

42

42 The corThe corThe corrrrrrect ansect ansect answwwer is (B)er is (B)er is (B) All the elements on the periodictable were combined in the fusion furnace of some past star In

PRACTICE TEST 3

fact all substances in existence were formed from elementswhich were formed in stars.

43

43 The corThe corThe corrrrrrect ansect ansect answwwer is (B)er is (B)er is (B) The toy rocket achieves zero ity at the exact top of its flight when it is not moving upwardnor is it moving downward It is constantly accelerated towardthe earth while it is in free fall

veloc-44

44 The corThe corThe corrrrrrect ansect ansect answwwer is (A)er is (A)er is (A) The force pairs discussed in thethird law are equal in magnitude, oppositely directed, andoperate on differing bodies

sinθ Note that as the angle becomes

smaller, its sine also becomes smaller This causes the tension inthe line to increase drastically

V

Ω= 6 ampere

48

48 The corThe corThe corrrrrrect ansect ansect answwwer is (E)er is (E)er is (E) A chain reaction (industrial fission is

a chain reaction) continues because of the neutrons that are

emitted in the fissioning of each U-235 atom.

49

49 The corThe corThe corrrrrrect ansect ansect answwwer is (E)er is (E)er is (E) The largest force a magnetic fieldexerts on a moving charged particle occurs when the particlecrosses the most lines of force This occurs when the particleenters a magnetic field at right angles to the field

50

50 The corThe corThe corrrrrrect ansect ansect answwwer is (E)er is (E)er is (E) The process of reflection occurs

ANSWERS AND EXPLANATIONS

an electric potential of 1 volt.

54

54 The corThe corThe corrrrrrect ansect ansect answwwer is (D)er is (D)er is (D) The potential energy transformsinto kinetic energy, or the pile driver falls At the end of the fall,all the kinetic energy the pile driver has is converted into fric-tional work to drive the post into the ground

55

55 The corThe corThe corrrrrrect ansect ansect answwwer is (A)er is (A)er is (A) The longest leg the dog walked isthe eastward vector The fact that some of the length of thevector was later cancelled when the dog walked in the oppositedirection does not change the length of the individual vector.56

56 The corThe corThe corrrrrrect ansect ansect answwwer is (E)er is (E)er is (E) After the zeroth fringe, each brightspot represents a position of convergence for the two lightbeams The bright spots represent the number of whole wave-lengths difference in the path length taken by one of the lightbeams compared to the other light beam

57

57 The corThe corThe corrrrrrect ansect ansect answwwer is (C)er is (C)er is (C) The car rolls down a 20 m longincline that is raised at 15° from the horizontal Using trigonom-etry (sin 15°)(20 m) we find the car “falls” 5.125 m Using the PE

59 The corThe corThe corrrrrrect ansect ansect answwwer is (D)er is (D)er is (D) While the light ray is moving

through an optically denser material, its velocity decreases.60

60 The corThe corThe corrrrrrect ansect ansect answwwer is (C)er is (C)er is (C) The light ray is refracted toward thenormal passes through the glass and is incident on the mirroredsurface The angle of incidence equals the angle of reflection,and the light ray reflects toward the same surface it entered At

PRACTICE TEST 3