SCIENCE LEVELED EXAMS 03



SCIENCE LEVELED EXAMS 03 -

- HARD

1.

E In elastic collisions, none of the energy is lost in

deformation of the objects. Therefore, elastic collisions

conserve energy. Elastic collisions, along with inelastic

collisions, also conserve momentum. Thus, elastic collisions

conserve both energy and momentum, while inelastic

collisions only conserve momentum. [USRG:22,1,4]

2.

E Both mass and charge are inherent properties of objects.

These properties must be tied to an object and cannot exist

as independent entities in space. That is, a charge must be

carried by an object, it cannot exist by itself. [USRG:38,1,2]

3.

C According to Snell’s law, the angle of refraction as light

passes from medium 1 to medium 2 can be found by

considering the angle of the light ray in medium 1 and the

indices of refraction for both mediums. In equation form,

n1sin.1 = n2sin.2. Thus, the closer the indices of refraction

are for mediums 1 and 2, the less the angle of light travel

will change. Glass has an index of refraction of 1.5, which

is most similar to 1.45, the index of refraction for oil.

[USRG:30,2; USRG:35,1; USRG:35,2,1]

4.

A Recall that current flows in the opposite direction of

electron flow by convention. Thus, the current flows to the

right in this scenario. Using Right Hand Rule 1, point the

thumb to the right, then curl the remaining fingers. At the

top of the wire, the fingers point forwards. Therefore, the

magnetic field lines point forwards at that point. Note that

while distance from the wire does impact the strength of

the magnetic field, it will not alter the direction of the

magnetic field. [USRG:44,2,2; USRG:51,1,2]

5.

D Studies of dynamics focus on the causes of motion. Sir

Isaac Newton was the first scientist to focus on dynamics,

and he determined three laws about the causes of motion.

[USRG:15,1,2]

6.

D Using Right Hand Rule 2, the thumb must follow the

electron’s motion and point right while the index finger

follows the field lines and points forward. This leaves the

middle finger directed down for the force. The electron,

though, has a negative charge. This charge means that the

direction of the force must rotate 180° and point upwards.

[USRG:52,1,3]

7.

C A wave’s wave velocity equals its frequency times its

wavelength. It measures how rapidly the wave as a whole

propagates through its medium. In this example, 20 Hz

times 5 m equals a wave velocity of 100 m/s. [USRG:28,2,4]

8.

A Energy cannot be created or destroyed in any system,

although it can be transformed into a different form or

transferred. Conservative force, by definition, does not alter

an object’s energy. Although work is defined as force times

distance traveled, an alternate equation is W = .KE. The

conservation of momentum, however, does not indicate

conservation of energy. In inelastic collisions, while

momentum is conserved, energy is not. [USRG:18,1,4; USRG:19,2,1;

USRG:19,2,2; USRG:22,1,4]

9.

E A common unit system is the SI system. SI stands for

Système International, or in English, International System of

Units. The SI system is easily to use because the different

units are related to one another by factors of 10. [USRG:6,1,2]

10.

A The coulomb force occurs between two separated charged

objects. It equals the charge of object 1 times the charge of

object 2 times the electrical constant, all divided by the

distance between the two charged objects squared. Like

gravitational force, the coulomb force is inversely related to

the distance squared. The coulomb force, however, is

significantly stronger than the gravitational force. [USRG:39,2,1]

11.

E Circular motion is more complex than linear motion. The

variables that are used in linear kinematic equations are

modified to include the object’s shape for circular motion.

The analogous variable for force is torque. Torque can be

found using the equation rF. [USRG:24,2,4]

12.

E

Longitudinal waves are waves where displacement occurs in

the same direction of the wave’s motion. This displacement

occurs in the form of a fluctuation in density or pressure in

the medium. A common example of a longitudinal wave is

the sound wave. Please note that light waves, which classify

as electromagnetic, are transverse waves. [USRG:30,2,2]

13.

B

Magnets produce fields that are represented by field lines.

Field lines close together indicate a strong magnetic field.

In bar magnets, the field lines leave the magnet at the

north/positive pole and reenter at the south/negative pole.

The field lines also pass through the magnet, traveling from

the south to the north pole. In theory, the field lines

represent the effect of a positive monopole. Due to electron

spinning, however, monopoles do not actually exist. The

field lines represent a theoretical force. [USRG:51,2,3; USRG:52,1,0]

14.

D In 1820, Hans Christian Oersted discovered that placing a

compass near a current carrying wire moves the compasses

needle. This observation implied magnetic activity from an

electric current. Previously, electricity and magnetism were

thought to be entirely unrelated. In light of Oersted’s work,

that view was questioned. Many years later, in 1864, James

Maxwell linked electric and magnetic activities more

completely using four equations. [USRG:50,2,1]

SCIENCE LEVELED EXAMS 03 PAGE 10 OF 12

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15.

A Young’s experiment directs light through two closely placed

slits, essentially creating two light sources a small distance

apart. In doing so, the setup enables researchers to study

path length differences and the subsequent wave

interference. Young’s experiment produces alternating

bands of brightness and darkness, corresponding to regions

of constructive and destructive interference. [USRG:32,1,0]

16.

A

Position is defined as the location of an object relative to

the origin. Displacement, on the other hand, is the change

of position over a give time frame. This value eliminates the

dependence of the origin via subtraction of initial position

from final position. Since distance, velocity, and

acceleration are all calculated from displacement, they are

also independent of the location of the origin. [USRG:10,1,3;

USRG:10,1,4; USRG:10,1,5; USRG:10,2,2; USRG:10,2,5]

17.

A

Conservative forces do not alter the energy of an object’s

energy. They may convert the energy from one form to

another, however. A non-conservative force, on the other

hand, changes the energy on an object. Kinetic friction

reduces the energy found in a moving object, and is a non-

conservative force. Please note that kinetic energy is a scalar

quantity and not a force. [USRG:20,1,1]

18.

A

There are two types of friction – static and kinetic. Static

friction occurs while attempting to move a stationary

object. It varies in proportion to strength of force applied

to the object, although it does have a maximum value.

Once the maximum is reached, the object begins moving

and any friction becomes kinetic friction. [USRG:16,1,2]

19.

A According to Faraday’s law, a change in flux through a

closed conductor, such a wire loop, induces a current. This

current will induce a magnetic field that opposes the

change in flux. If a magnet moves towards a wire loop, it

increases the flux through the loop. The current induced

would aim to reduce the flux through the loop. By Right

Hand Rule 1, this opposition occurs with a counterclockwise current through the loop. [USRG:55,2,1]

20.

A

There are several key kinematics variables. The most basic

is position, which is the distance from the origin. Changes

in position are used to find displacement. Position is the

only variable that depends on the location of the origin.

[USRG:10,1,3]

21.

B

According to Snell’s law, n1sin.1 = n2sin.2, where n

represents the indices of refraction for medium 1 and

medium 2, and . represents the angle from the normal

along which the light ray travels in mediums 1 and 2.

Water has an index of refraction of 1.33, and diamond’s

index of refraction is 2.4. Since diamond has the larger

index of refraction, it must have a smaller angle from the

normal for Snell’s law to hold true. That leaves only 11°

and 0° as options. 0°, however, represents a sine value of 0,

making Snell’s law impossible to calculate. Therefore, 11° is

the only reasonable answer. [USRG:30,2; USRG:33,2,2; USRG:35,1]

22.

D

Kinematics problems use multiple vector quantities. In

vectors, both magnitude and direction are important

factors. Therefore, it is necessary to define a coordinate

system before beginning other calculations. This method

allows vector directions to be assigned without confusion.

[USRG:10,1,2]

23.

A

While placing resistors in series increases the equivalent

resistance, resistors placed in parallel produce a lower net

resistance. Of the two options that place resistors in

parallel, it should be intuitive that more resistors in parallel

will decrease the total resistance by a bigger factor. This

assumption is easily confirmed by some quick calculations.

While two resistors of 1 ohm in parallel produce an

equivalent resistance of 0.5 ohms, three resistors drop the

resistance even further, to 0.33 ohms. [USRG:46,2,3; USRG:47,1,2]

24.

E

Several subatomic particles exist. Almost all of these

particles are either positively charged, like the proton, or

negatively charged, like the electron. The only sub-atomic

particle that lacks a charge is the neutron. [USRG:391,2]

25.

D In 1820, Hans Christian Oersted discovered that placing a

compass near a current carrying wire causes the compass

needle to deflect away from north. This discovery was the

first evidence that electricity and magnetism are related

concepts. Since that time, electricity and magnetism have

been more thoroughly connected, primarily through the

work of James Maxwell. [USRG:51,1,0]

26.

A

The most common path to scientific discovery is through

the scientific method. There, scientists ponder questions,

make and test hypotheses, and analyze the results. Most

often, the results cause the scientist to adjust his or her

original hypothesis. This new hypothesis is subjected to

new testing. After many round of this cycle, some scientific

knowledge may be observed. [USRG:5,2,1]

27.

B In series circuits, the sum of the voltage drops across all

resistors equals the battery induced voltage drop. Also,

Ohm’s law states that .V = IR. In this scenario, the voltage

drop across resistor 1 will equal 15 volts, while the drop

across resistor 2 will equal 5 volts. Totaled, this produces a

potential difference of 20 volts. [USRG:46,1,0; USRG:46,1,1; USRG:46,1,2]

28.

E While conductors have relatively low resistances, insulators

tend to have high resistances. Thus, conductors will have

lower resistances than insulators. Metals make good

conductors. Of the materials listed, the only metal is silver.

[USRG:41,1,4; USRG:41,2,1; USRG:43,2,5]

29.

D

Light rays represent the complex transverse waves of light

that travel in straight lines. These rays start at an object and

radiate outward for an indefinite distance, at least in theory.

In real life, gases or other mediums may absorb they light

rays. Human eyes focus the diverging rays to determine

distance from the original object. James Maxwell

determined that light waves have an electromagnetic

nature. [USRG:32,2,5; USRG:33,1,1; USRG:56,2,0]

SCIENCE LEVELED EXAMS 03 PAGE 11 OF 12

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30.

D Energy is found via the equation 1/2mv2. The units for

energy are joules, and they also equal kilograms times

(meters per second)2. [USRG:18,2,2]

31.

E

It is often difficult to draw field lines going into the paper.

The symbol X is currently used to draw such lines. The use

of this symbol eliminates confusion over whether or not the

field lines are in the plane of the sheet of paper. [USRG:52,2,3]

32.

C

Total Internal Reflection occurs when the angle of

refraction directs the incident light ray back into the

original medium. This can occur when light passes from a

slower medium to a faster medium. Fiber optics technology

uses this behavior to send data. [USRG:35,1,0]

33.

D

Magnetic behavior originates with spinning electrons. In

some materials, the spins of the electrons total fro produce

appreciable magnetic behavior. These materials classify as

ferromagnetic and include some metals, like iron. [USRG:53,1,2]

34.

A According to Kirchhoff’s loop rule, the sum of all the

potential changes across any closed circuit loop must equal

0. Essentially, this rule states that a circuit loop can neither

create nor destroy electric potential, making this rule an

application of the conservation of energy. [USRG:47,2,2]

35.

E

A medium’s index of refraction is found by dividing the

speed of light in a vacuum by the speed of light in the given

medium. Large indices of refraction indicate a slow

medium, while indices closer to 1 indicate a fast medium.

Oil has an index of refraction equal to 1.45. [USRG:30,1,3;

USRG:35,1]

36.

A Sound waves propagate as a change in density or pressure.

When the medium through which a sound wave travels has

closely placed particles, the sound wave can spread quickly.

In other words, denser mediums carry sound more rapidly

than less dense mediums. Helium, which is a gas, has the

least dense particles. Accordingly, sound waves will travel

slowly through helium. [USRG:30,2,2]

37.

A In parallel circuits, the voltage drop across each resistor

equals the voltage difference established by the battery.

According to Ohm’s law, .V = IR. Therefore, in this

circuit, 20 volts divided by 10 amperes indicates a

resistance of 2 ohms. Note that the resistance of resistor 1 is

irrelevant to this calculation, because the current running

through the other branches of the circuit will differ from

the current flowing through the branch of interest.

[USRG:46,2,6; USRG:47,1,0]

38.

C

Human eyes can perceive light rays with wavelengths

ranging from 400 to 700 nm. Red has the longest

wavelength while violet has the shortest wavelength.

Human eyes are most sensitive to yellow-green light with a

wavelength of 560 nm. [USRG:30,1,2]

39.

D

To add vectors, place the tail of the second vector at the

head of the first vector. In this set-up, vector B points east

from a point 3 meters north of the origin (the head of

vector A). Therefore, vector C will point northeast. Some

simple right triangle math confirms that the length of the

vector is 5 meters. [USRG:8,2,4]

40.

D

There are three basic units that describe all the

measurements, when used in combination. These units

include mass, length, and time. Any other unit is a

combination of some or all of those three units. For

instance, velocity uses the combination of length per time.

[USRG:6,1,3]

41.

E Kinematics calculations revolve around four key equations.

Any given equation contains four of the five kinematic

variables (displacement, time, initial velocity, velocity at a

given time, and acceleration). All of the equations,

however, include initial velocity as a variable. Therefore, in

any calculation, initial velocity must either be known or be

calculated. [USRG:11,2]

42.

C

Wave variables depend on the nature of the medium, the

wave source, or some combination of the two. Frequency

depends only on the rate of the wave source. On the other

hand, amplitude depends on both the force of the wave

source and the nature of the medium. [USRG:29,1,2]

43.

C According to Faraday’s law, a changing magnetic flux

through a wire loop will induce a current in the wire. This

current is driven by a potential difference, or an

electromotive force. The current will also induce a new

magnetic field in opposition to the change. [USRG:54,1,3]

44.

C

Kinetic energy refers to energy in the form of motion. To

calculate kinetic energy, use the equation KE = 1/2mv2,

where m represents mass and v represents the object’s

velocity. The equation mgh represents potential energy, ma

represents net force, Fd represents work, and mv represents

momentum. [USRG:18,2,1]

45.

E

Flux is maximized when the field lines are densest within

the area. With bar magnets, field lines are very dense at

both the north and south poles. Still, the field lines are at

their densest within the magnet. Therefore, placing the

magnet within the wire loop will maximize flux. [USRG:52,1,0;

USRG:55,1,2]

46.

C

Potential is often only considered when looking at the

change in potential. If the potential does not change

between points A and B, then the electric field must be the

same at both of those points. Therefore, movement

between the two points had to be perpendicular to the

electric field. [USRG:42,2,0]

47.

A

While some properties of waves depend only on the wave

source, others depend solely upon the nature of the

medium. A few properties depend on both the wave source

and the medium. Amplitude changes based on the nature

of the medium and the amount of force the wave source

applies to the medium. [USRG:29,1,3]

48.

C

Electric potential examines the potential energy of a

charged particle in an electric field without referencing the

value of the test charge. It is found by dividing the electric

potential energy by the test charge. Since the electric

potential energy equals k(q0q1/r), dividing that value by q0

give the equation V = k(q1/r). [USRG:42,1,4]

49.

C

Impulse is defined as force applied over a time period.

Impulse essentially describes how a force changes an

object’s direction. This change in direction, as for example

in a collision, causes a change in momentum. An

alternative definition of impulse is the change in

momentum. [USRG:21,2,2]

50.

D

Beats are heard when two sound sources produce sounds

with slightly different frequencies. The frequency difference

creates a pattern of alternating constructive and destructive

interference that is heard as beats. The frequency of the

beats equals the frequency difference between the two

sounds. Musicians try to minimize this beat frequency

when tuning instruments. [USRG:32,2,5]

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