8th Physical Science PHYSICS PART 2 STUDY GUIDE - Answer Sheet 1) Gravity on the moon is about

1

6 th the gravity felt on the earth. This is because

A) the moon is so far away from the earth.

B) the moon is much less massive than the earth.

C) the earth has a molten core and the moon doesn't.

D) the moon is so much further from the sun than the earth.

Explanation: The size of the object determines the gravitational attraction of it, and the moon is much less massive than the earth. 2) Ultraviolet radiation is dangerous because it has a high enough energy to damage skin cells. UV radiation is called ultraviolet

because it has a frequency which is higher than violet radiation (purple light). Therefore, it has a wavelength which is ___________ than violet radiation.

A) bigger

B) smaller

C) the same size

D) the square root of

Explanation:

Frequency and wavelength are inversely proportional. This means that as one goes up, the other goes down. Since the frequency of UV light is larger, its wavelength must be smaller. 3) An echo is an example of sound wave

A) diffraction.

B) interference.

C) reflection.

D) refraction.

Explanation: An echo is the bouncing back of a sound wave off of a surface, this is reflection. 4)

The picture lists light waves from left to right in order of highest to lowest energy. Which region of the electromagnetic spectrum has the longest wavelength?

A) UV

B) Gamma Rays

C) Radio Waves

D) Visible Light

Explanation: Radio waves have the lowest energy, lowest frequency and, due to the inverse relationship, the longest wavelengths. 5) After turning off the television, you approach it. As you get close, but not touching it, the hairs on your arm start to stand up. This is

an excellent example of static charge built up by

A) conduction.

B) convection.

C) friction.

D) induction.

Explanation: This is static build up by induction. In this case, the charge from the television screen has attracted the opposite charge on your body.

6) A scientist is giving a demonstration with a Van de Graaff generator in a class about electrostatics. The scientist can detect the type

of charge on the Van de Graaff generator by

A) bringing a positively charged balloon near it.

B) seeing if it picks up bits of paper from a surface.

C) touching it with a metallic rod that conducts charge.

D) testing if it attracts a neutral sphere made of plastic.

Explanation:

If the Van de Graaff generator is positively charged, it will repel a positively charged balloon. If the generator is negatively charged, it will attract the balloon. Thus, the type of static charge can be detected by bringing a positively charged balloon near it. The other

answer choices tell us nothing about the type of charge. 7)

Which form of radiation from the electromagnetic spectrum is MOST LIKELY to cause mutations in growing tissues, and should be MOST avoided by pregnant women?

A) microwaves

B) gamma rays

C) radio waves

D) ultraviolet rays

Explanation:

Gamma rays are the highest in energy, and therefore cause the most damage. Cancers, mutations and cell damage can easily occur with exposure to large amounts of gamma radiation. 8) You attend a football game one day and notice a long time difference between when the other side of the stadium stands up to cheer

and when you hear them. This time difference would be lessened if

A) it were warmer.

B) it were less humid.

C) it were located at a higher altitude.

D) the fans on the opposite side shouted louder.

Explanation: If it were a warmer temperature, the air molecules would be moving faster. If particles are moving faster, they can transmit sound

faster. 9) The speed of sound is greater through a solid than through a gas because the molecules in a solid are

A) still.

B) vibrating.

C) farther apart.

D) closer together.

Explanation:

Sound is vibrating molecules and the closer the molecules are, the more quickly they bump into one another. In a solid, molecules are closer together. 10) The circumstance MOST LIKELY to cause a compass to give an erroneous reading is standing too close to

A) the ocean.

B) a mountain.

C) an electric power line.

D) a heavily populated area.

Explanation: The electric current that came from standing too close to a power line might cause a compass to point incorrectly. 11) Longitudinal waves compress the medium they travel though. One example of a longitudinal wave is a

A) sound wave.

B) ocean wave.

C) infrared wave.

D) ultraviolet wave.

Explanation: Although both ocean waves and sound waves need a medium, only a sound wave compresses the medium. Infrared and ultraviolet

waves are electromagnetic waves or transverse waves. 12) Sal and Marie were experimenting with bar magnets in science class, picking up chains of paper clips. Where should they expect

the magnetic force of the bar magnet to be the strongest and pick up the most paper clips?

A) at both Poles

B) at the South Pole

C) at the North Pole

D) in the center of the bar magnet

Explanation: A bar magnet will be the strongest and pick up the most paper clips at each end or at both Poles. The magnetic force field is strongest

in the corners of the Poles and weakest along the surface in the middle of the magnet. 13)

The distance shown in the diagram is known as the

A) amplitude.

B) crest.

C) trough.

D) wavelength.

Explanation: The distance shown here changes as a wave gains or loses energy and is known as its amplitude. It is the distance from base line to

crest or base line to trough. 14)

What factor is responsible for altering the speed of an electromagnetic wave?

A) amplitude

B) wavelength

C) type of medium

D) frequency of the wave

Explanation:

All electromagnetic waves travel at the same speed regardless of frequency, wavelength, or amplitude. The factor that influences the speed of an electromagnetic wave is the type of medium the wave is passing through. 15) It seems like everyone has a cell phone these days. Sounds, images, and the written word can all instantly be sent using this

technology. How do cell phones send information from one person to another?

A) Sound waves are sent through the air.

B) Sound waves are sent through overhead cables.

C) The signals are sent through underground cables.

D) The signals are sent through communication satellites.

Explanation: The signals are sent through communication satellites. Cellular phones work on wireless technology. 16)

__________ lenses refract light rays in toward a central point. When this lens is held close to your eye, the image is magnified and right side up.

A) Concave

B) Convex

C) Prismatic

D) Refractive

Explanation: Convex lenses refract light rays in toward a central point. We often use these lenses to magnify objects. But if the lens is held far from

your eye, the image seem through a convex lens will be upside down. 17)

As the band passed by, the beating drums and trumpets made Billy feel like his body was beating with the music. He could hear the music and he could feel it! How would a scientist explain this to Billy?

A) Sound waves cannot travel through the air

B) Sound waves transmit energy through all forms of matter.

C) The marching causes the ground to move which Billy feels

D) Sound waves are transmitted faster through gases than through solids.

Explanation: Sound waves transmit energy through all forms of matter. Sound waves do cause the air to vibrate, but they may also cause the

ground as well as Billy to vibrate because sound waves can be transmitted through solids and liquids, not just air or gases. 18) When Jamie removes a woolen cap, his hair develops an excess of static charge Which of these BEST explains this phenomenon?

A) Electrons are transferred from the woolen cap to Jamie’s hair.

B) Electrons are transferred from Jamie’s hair to the woolen cap.

C) Positive charges are transferred from the woolen cap to Jamie’s hair.

D) Positive charges are transferred from Jamie’s hair to the woolen cap.

Explanation: When a woolen cap rubs Jamie’s hair, electrons are transferred from Jamie’s hair to the woolen cap. As a result, his hair turns

positively charged, and the cap turns positively charged. This happens because hair gives up electrons more readily than wool. Note that positive charges do not get transferred; only electrons can get transferred. 19)

The figure shows a negatively charged sphere and a balloon that has been rubbed with dry human hair. If the two are brought close to each other but do not touch each other, you can predict that the objects will

A) repel each other.

B) charge each other.

C) attract each other.

D) polarize each other.

Explanation:

First, we need to recall that when a balloon is rubbed with human hair, the balloon becomes negatively charged because electrons are transferred from hair to the balloon. The sphere is also negatively charged. If the balloon and sphere are brought close to each other, the two objects will repel each other because they both have a similar charge. 20) Maria and Sarah made a set of paper cup telephones. First the girls punched a hole in the bottom of each cup. Then they

connected the cups with a very long piece of string, knotted in the bottom of each cup. Maria went down the hall to her bedroom while Sarah stayed in the kitchen. When Maria put the cup to her ear she could hear Sarah talking to her because.

A) they were not that far from each other.

B) sound waves traveled through the string to Maria’s cup.

C) sound waves traveled through the air from room to room.

D) sound waves bounced off of the walls to reach Maria in the bedroom.

Explanation:

Sound waves are vibrations that form compression waves. They travel fastest through solids, like the string. Maria could hear Sarah talk because sound waves traveled through the string to Maria’s cup and then to Maria’s ear. 21) Which phenomenon causes an object to appear bent from above the surface of one medium to below the surface of another

medium?

A) diffraction

B) dispersion

C) reflection

D) refraction

Explanation: Refraction is the phenomenon that causes an object to appear bent from above the surface of one medium to below the surface of

another medium. 22) What happens when light strikes a transparent object?

A) All the light passes through the object

B) None of the light passes through the object

C) All of the light is reflected then reabsorbed

D) Some of the light is scattered or absorbed and some passes through.

Explanation: All the light passes through the object. Glass, like in a windshield, is a transparent object. 23)

Sara is using a magnifying glass to closely examine her stamp collection. Why type of lens is found in a magnifying glass?

A) bifocal

B) concave

C) convex

D) prismatic

Explanation: Magnifiers contain one convex lens. A convex lens has a thick middle and thin edges. 24) Reflection is the bouncing of light rays off of a surface. Which situation is NOT an example of reflection?

A) looking at yourself in a mirror

B) focusing light through a camera lens

C) seeing an image of yourself in a still lake

D) looking at your teacher at the front of the class

Explanation:

A and C are cases where light is bounced and reflected off a surface. What seems a little strange is that whenever you see anyone or anything, the reason you see them is that light (from the sun, or from electric lights) actually bounces off of them to get to your eye so you can see them. This leaves focusing light through a camera lens which is actually an example of refraction. 25)

Which change would result in a stronger electromagnet?

A) using a smaller battery

B) using an iron nail with a larger diameter

C) changing the core to something made of aluminum

D) decreasing the number of wire coils around the nail

Explanation: Using an iron nail with a larger diameter will increase the strength of the electromagnet. So will increasing the number of batteries or

the number of wire coils wrapped around the nail. 26)

Reva placed an iron nail close to a magnet. What happened?

A) The nail bent.

B) The nail moved to the magnet.

C) The nail stayed in the same place.

D) The nail pushed away from the magnet.

Explanation: Iron is attracted to magnets. When an iron nail was placed close to a magnet, the nail moved to the magnet. 27)

A convex lens bulges outward in its center. and it refracts light rays towards its center. Which represents a convex lens?

A) A

B) B

C) A and B

D) neither A nor B

Explanation: A convex lens has a shape like A. The lens bulges outward in its center, like reading glasses. 28)

Mary touched the Van de Graaff generator and all her hair stood on end. The charge from the generator was transferred to Mary's hair so all of the strands had the same + charge. Her hairs all repelled each other and stood on end like you see here. This illustrates what

law?

A) law of gravity

B) law of electrons

C) law of attraction

D) law of electricity

Explanation: This illustrates the law of attraction because like charges repel and opposite charges attract. 29)

Braddy connected the lose wire to the battery and created an electromagnet. He picked up 45 thumb tacks with his electromagnet, though his goal was to pick up 50 thumb tacks. What could Braddy do to increase the strength of his electromagnet and pick up more thumbtacks?

A) Use fewer coils of wire.

B) Use a screw instead of a nail.

C) Use two batteries instead of one.

D) Replace the nail with a piece of steel.

Explanation: Braddy could use two batteries instead of one.

One way he could increase the strength of his magnet is to increase the current and add a second battery. He could also add more coils of wire, not use fewer. 30) CD's and DVD's both are applications of light. Light is used to read the information on the disc. Which property of light is used in

this technology?

A) Diffraction

B) Interference

C) Reflection

D) Refraction

Explanation: Reflection is used to read the information on the discs. 31)

What statement explains the changes from wave A to wave B?

A) The energy and amplitude increase.

B) The energy and amplitude decrease.

C) The energy decreases as the amplitude increases.

D) The energy increases as the amplitude decreases.

Explanation: What statement explains the changes from wave A to wave B? The energy and amplitude increase. 32)

Sound travels in waves. Sound waves cannot travel through

A) air.

B) solids.

C) space.

D) water.

Explanation: Sound waves can only travel through a medium. Sound waves cannot travel through space. 33)

Which choice BEST represents the sound waves from a soft low-pitched train rumble that suddenly shifts to a loud, high-pitched squeal of brakes?

A)

B)

C)

D)

Explanation:

The short, spread out sized wave of low-pitched, soft sound is going to change to a tall rather squished-looking wave as is seen in choice A. 34) Eyeglasses bend light help the image form properly on the retina. The bending of light as it passes from one medium to another is

called

A) diffraction

B) interference

C) reflection

D) refraction

Explanation: The bending of light when it changes speed as it passes from one medium to another is called refraction. 35)

Based on the images seen here, identify which phase of matter would transmit sound waves the fastest, and why?

A) The gas would transmit the fastest because the particles move the fastest.

B) The solid would transmit the fastest because the particles are closest together.

C) The liquid would transmit the fastest because the particles are the most freely moving.

D) The gas would transmit the fastest because there are the fewest particles to interfere with the waves.

Explanation: The solid would transmit the fastest because the particles are closest together. Sound energy can transmit from one particle to

the next quicker if the particles are close together. 36) If your new bike is painted so that it looks red, what color of light is reflected by the paint?

A) blue

B) indigo

C) red

D) violet

Explanation: The red light waves are reflected.

If any colors of light are reflected by an object then that object will look the same color as the reflected light. 37)

In the old west, a cowboy would put their ear on the railroad track to determine if a train was coming. Using this method, they could

tell if the train was coming sooner than just listening for the train.

A good explanation for this would be that

A) sound and vibrations travel faster through gases than solids.

B) sound and vibrations travel faster through solids than gases.

C) sound and vibrations dissipate faster in solids than in liquids or gases.

D) sound and vibrations are more concentrated in solids than in liquids or gases.

Explanation: The speed of sound is dependent on medium. Sound and vibrations travel faster through solids than gases. 38) You rub a balloon on your head and it becomes negatively charged. The balloon will be MOST attracted to

A) a piece of metal.

B) positively charged hair.

C) the neutrally charged wall.

D) another negatively charged balloon.

Explanation: It will be attracted most to your positively charged hair. This is why it will make it stand on end. Unlike charges attract, like charges

repel. 39) Mrs. Adams class decides to try an experiment. She rubs a blown up balloon on Sandy's head. After this, she takes the balloon and

places it on the side of the wall, where it sticks, instead of falling to the ground. Also, Sandy's hair is now sticking almost straight out. What causes Sandy's hair to act this way?

A) magic

B) wind currents

C) static electricity

D) current electricity

Explanation: Rubbing the balloon on hair produces static electricity. This force can make your hair stand on end and also makes the balloon stick

to the wall. 40)

A table has several directional compasses, several lengths of wire, an iron nail, a battery, an ammeter, a light bulb, a permanent

magnet, several metal paper clips and a rubber eraser.

A student is asked to build and demonstrate a working temporary magnet. From the items on the table, which items can be used together to accomplish this task?

A) A battery, an iron nail, a wire and several paper clips will accomplish this task.

B) An ammeter, an iron nail, a wire and several paper clips will accomplish this task.

C) A battery, a wire, a permanent magnet and several paper clips will accomplish this task.

D) A battery, an iron nail, a permanent magnet and several paper clips will accomplish this task.

Explanation: A battery, an iron nail, a wire and several paper clips will accomplish this task. Wrap the wire around the nail and apply a current

using the battery. This should create an electromagnet that could pick up several paper clips. 41) A high school website directs parents to not allow student access to blue laser pointers or allow the students to bring them to

school. It includes a video describing the danger inherent in the misuse of all laser pointers particularly the blue laser pointer. Why would they claim that blue laser pointers are more of a concern than red laser pointers?

A) Colored light falls into the visible region and the red light has a smaller wavelength and higher energy than blue light.

B) The wavelengths and energies differ. The ultraviolet blue light has a larger wavelength and smaller energy compared to infrared.

C) Both wavelengths fall into the visible light region but blue light has a smaller wavelength and higher energy than red light.

D) These colors have similar wavelengths but the blue laser light has more energy than red laser light making it more dangerous.

Explanation: Both wavelengths are fall into visible light region but blue light has a smaller wavelength and higher energy than red light. 42) A Wi-Fi hotspot is an area with an accessible wireless network. The term is most often used to refer to wireless networks in public

areas like airports and coffee shops. Some are free and some require fees for use, but in either case they can be handy when you are on the go. Just like cellphones and televisions, wi-fi works by utilizing ______________ to transmit signals and data.

A) radio waves

B) microwaves

C) ultraviolet rays

D) infrared waves

Explanation: Wi-fi works by utilizing radio waves to transmit signals and data.

Communication across a wireless network is a lot like two-way radio communication. Here's what happens: 1) A computer's wireless adapter translates data into a radio signal and transmits it using an antenna. 2) A wireless router receives the signal and decodes it. The router sends the information to the Internet using a physical, wired Ethernet connection. 43)

Mary's class is studying sound waves. Mary played two sounds on her flute. For the first sound, Mary blew gently. For the second sound, Mary blew into the flute with a lot of force. What change can you hear?

A) The second flute sound is louder than the first.

B) The first flute sound has a higher pitch than the second.

C) The two flute sounds are the same because they are the same note.

D) The second flute sound has a lower pitch and is louder than the first sound.

Explanation: The second flute sound is louder than the first. The wavelengths are the same so the pitch or note does not change. The amplitude

is greater for the second sound so it is louder. 44) A remote control only works when it is pointed at the television. What is the best explanation for this?

A) The remote control has a weak signal and will only work over short distances.

B) The remote control transmits information at the speed of light to the television.

C) The remote control transmits information that is encoded and the television decodes it.

D) The remote control transmits information through waves, such as infrared waves, to the television.

Explanation: The remote control transmits information through waves, such as infrared waves, to the television.. So, there must be a line of

sight from the remote to the television. 45) The harder you strike a drum, the greater the sound’s

A) medium

B) volume

C) frequency

D) pitch

Explanation: The correct choice is volume because it is the loudness of a sound. 46)

Examine the pattern of the wave shown. What is true about the amplitude and wavelength of the wave when the pattern changes?

A) Both the amplitude and wavelength of the wave increase.

B) Both the amplitude and wavelength of the wave decrease.

C) The amplitude of the wave increases while the wavelength decreases.

D) The amplitude of the wave decreases while the wavelength increases.

Explanation: The amplitude of the wave increases while the wavelength decreases.

Wavelength is the distance between one crest or trough to the next and amplitude is the height of the wave from the point of equilibrium. 47)

A concave lens has an inward curved shape. It refracts light outward from the lens. The light rays spread apart as they exit the lens. Which represents a concave lens?

A) A

B) B

C) A and B

D) neither A nor B

Explanation: A concave lens has a shape like B. The lens has a curved inward shape. 48) A student looks at ocean waves coming into the beach. An ocean wave with more energy will

A) have a greater height.

B) have a greater period.

C) travel toward the beach faster.

D) strike the beach with greater frequency.

Explanation: The energy of a wave is proportional to the amplitude and will have a greater height. 49)

The attracting and repelling forces of magnets are used in countless objects, from refrigerator doors to maglev trains. Refrigerator doors use the attraction of magnets to stay closed, while maglev trains use magnetic repulsion to hover above rails. The center magnet in the picture is hovering between two magnets, making it appear to float. Which best explains how the center magnet is able to hover between two other magnets?

A) The magnets are stacked so that similar poles are facing one another.

B) The opposite poles of each magnet are facing each other, so they repel.

C) The middle magnet is repelling the top magnet while attracting the bottom.

D) The middle magnet is attracted to the top magnet, but held down by gravity.

Explanation: The magnets are stacked so that similar poles are facing one another.

The repelling poles push against each other, so the magnet does not pull toward the top or bottom magnet. 50) In the military, night vision goggles are used to pull off secret missions into areas that are very dangerous. For this reason, the

soldiers try to infiltrate at night so they can't be seen. Thermal-imaging devices are often used as well to locate people on these highly secretive missions. What type of electromagnetic radiation is being utilized?

A) radio waves

B) gamma rays

C) ultraviolet rays

D) infrared waves

Explanation: Infrared waves are used in thermal-imaging devices as well as night vision cameras. They utilize the heat that is given off by humans

to transmit information and get a picture of where they are