# Conceptual Physics: Conceptual Physics Chapter 15+17+19+20+22+23 Flashcards

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12th Edition. Hewitt.
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1

What is temperature? What is absolute zero?

Temperature is the measure of average kinetic energy of molecules in a substance. Absolute zero is a substance which has absolutely no kinetic energy to give up.

2

How is heat transferred?

Heat is transferred from a warmer object to a cooler one. It is the energy transferred from one object to another because of a temperature difference. Matter does not contain heat, it contains molecular kinetic energy and potential energy.

3

Does a glass of water sitting on a table have any energy?

Yes, it has both kinetic and potential energy.

4

What is internal energy?

Internal energy is the grand total of all the energies in a substance. ex. there is more internal energy in a larger volume of water as opposed to a lesser volume.

5

What is the specific heat capacity of all substances?

The specific heat capacity of all substances is defined as the quantity of heat required to changed the temperature of a unit of mass by 1 degree celcius. (Q=MC^T).specific heat is thermal inertia. It signified the resistance of a substance to change in its temperature.

6

Which has a higher heat capacity, water or sand?

Water has a higher heat capacity.It has a greater thermal inertia and takes longer to warm in the hot sun and longer to cool on a cold night.

7

It takes 1 joule of energy to life an apple of 0.1kg, 1 meter. Convert this to calories.

1 calorie = 4.2 Joules

Mass - 0.1 KG

Formula = 0.1/4.2

= .0238 (round ->) = .24 cal

8

If an apple has 100 calories of food energy or stored chemical energy, convert this to calories and to joules.

1 Food Calorie - 4200 J

1 kilocalorie = 1000 cal

100 cals x 4200 J / 1 = 420,000 / 1000 = 420 KJ

9

What is the difference between the temperature of an object and the internal energy of an object?

The temperature of an object is the average translational kinetic energy per molecule of a substance.

The internal energy of an object is the TOTAL of all molecular energies in a substance. (KE + PE)

10

What makes one object hotter than the other? what makes one hot beaker and one cold beaker different than the other?

The molecules differ in speed. The hot water has faster moving molecules that move in a variety of speeds as opposed to the cold water, which has slower moving molecules.

11

Someone says that their soup is hot and that it contains a lot of heat. How would you correct them? Does the soup really contain heat?

The soup does NOT contain heat. In fact, it contains internal energy with fast moving molecules.

12

1. It takes 200 calories of heat to change 10 g of metal by 5 degrees Celsius. What is the amount of energy or heat it takes to change 1 g of this metal by 1 degree Celsius?

2. What is the specific heat of this metal?

3. How much heat does it take to heat 200 g of water by 80 degrees Celsius.

Q=MC^T

m= 10 g

^T= 5 degrees celsius.

Q = 200 cal

1. 200 KJ

2.

200 cal = 10 g (c) (5)

c = 200 / 10 (5)

c = 200 / 50

c = 4 cal * g *c

3. Q= ?

M= 200 g

^T = 80 *C

c = 1 cal g*C

Q= MC^T

Q= (200)(1)(80)

Q = 16,000 cal

13

A drop of water hits the ground with a speed of 10 m/s. If all the kinetic energy of the water were changed into heat, what would be the change in temperature of the water?

Formula = KE = ( 1/2 mv^2) = 3/2 kT

KE = 133 KT

14

A substance that heats up quickly has a:

a. High specific heat

b. Low specific Heat

b. lowspecific ehat

15

Compared to a giant iceberg, a hot cup of coffee has

a. more internal energy and a higher temperature

b. higher temperature, but less internal energy

b. Higher temperature but less internal energy

16

The fact that desert sand is very hot in the day and very cold at night is evidence that sand has

a. a low specific heat

b. a high specific heat

c. no specific heat

A. a low specific heat

17

The molecules in a room temperature glass of water jostle around at

a. A great variety of speed

b. Much the same rates of speed

c. A very small range of speeds

a. A great variety of speeds

18

To say that evaporation is a cooling process is to say that the

a. More energetic particles escape

b. more energetic particles remain in the water

c. the less energetic particles escape

a. more energetic

19

When a solid is changed to a liquid state, the solid

a. releases energy

b. absorbs energy

c. neither releases nor absorbs energy

b. absorbs energy

20

To increase the tempt of 50 grams of water by 2*C requires

a. 0.04 calorie

b. 2 calories

c. 4.18 calories

d. 25 calories

e. 100 calories

50 g x 2 *C = 100 calories

e. 100 calories

21

To melt 10 grams of 0*C ices requires

a. 10 calories

b. 800 calories

c. 100 calories

formula = Q=mHf (Hf=80)

Q = 10 (80)

Q = 800

b. 800

22

IF the frequency of a certain wave is 10 Hertz, its period is

a. 0.1 seconds

b.10 seconds

c. 100 seconds

Formula = T = 1 /F

T = 1 / 10

a. 0.1

23

Double the frequency of sound and you halve its

a. wavelength

b. speed

c. amplitude

a. wavelength

24

What is evaporation?

It is a change of phase from a liquid to a gas that takes place at the surface of a liquid. The faster moving molecules at the surface escape. It is a cooling process.

25

What is Condensation?

It is a change of phase from a gas to a liquid. It is a heating process.

26

Define Thermal Expansion.

Due to increased molecular motion, most material expand as temperature rises. for ex, sidewalks crack in the hot days of summer.

27

Define Sublimation.

The change of phase from solid to gaseous by passing the liquid phase.

28

what are waves caused by?

By a vibration or disturbance. ex. sound waves, light.

29

What are the two movements of waves?

Transverse "Up and down." and Longitudinal "Back and forth"

30

What type of wave is sound?

Longitudinal wave.

31

What is a medium? What are the two types of mediums.

What the wave travels through.

. Mechanical wave : Which needs a medium, like sound.

Electromagnetic wave: Can travel through empty space

32

What type of wave does light, radios, and cell phones need?

Electromagnetic waves.

33

What is Frequency?

The number of waves per time.

34

What is the speed of a wave affected by?

It is only affected by the medium and the type of wave.

35

As the frequency of a wave increases the period of the wave

a. decreases

b. increases

c. remains the same

a. decreases

36

The time for a wave to pass by is 0.25 seconds. What is the frequency of this wave or how many waves will pass by each second?

Formula : F = 1 / T

F = 1 / 0.25

F = 4 hz

37

AS the frequency of a wave in increases, the wavelength of the wave

a. increases

b. decreases

c. remains the same

b. decreases

38

A fly flaps its wings back and forth 150 times each second. The period of the wing flap is?

Formula: T = 1 / F

T = 1 / 150

T = 0.067 seconds

39

What is the wavelength of the lowest sound (20 Hz) that humans can hear?

Formula : S= Wavelength x F

Speed of sound = 340 m/s

F = 20 Hz

340 = ? x 20

? = 17 m

40

A sound wave has a frequency of 256 Hz. If the speed of sound in the air is 340 m/s, determine:

a. The wavelength

b. The period

c. if the frequency is doubled, what is wavelength.

S = wavelength x F

a. 340 = ? x 256

? = 1.3 m

b. T = 1 / F

1 / 256 = .0039 seconds

c. 256 (2) = 516 Hz

340 = wavelength x 512

wavelength = .66 m

41

What type of waves are radio waves? How fast do these waves travel?

Electromagnetic waves.

They travel at the speed of light (C= 3 x 10^8 m/s)

42

What is the wavelength of a radio wave with a frequency of 104.1 MHz ?

Formula : S = wavelength x F

F = 104.1 x 10^6

S = 3 x 10^8

3 x 10^8 = ? x 104.1 x 10^6

wavelength = 2.88 m

43

What is the wavelength of a radio wave with a frequency of 1080 kHz?

Formula: S = wavelength x F

S = 3 x 10^8

F = 1.08 x 10 ^6

3 x 10^8 = ? x 1.08 x 10^6

wavelength = 277 m

44

Explain how someone would be able to break a wineglass with only their voice?

By matching the pitch of your voice to the frequency of the glass.

45

What is the red shift and what does it say about the entire universe?

The red shift is a light source that is receding. It has a long wave length and short frequency. on the contrary, a blue shift has a short wave length and a higherfrequency. The red shift was observed in the galaxies so were expanding the universe.

46

What is the doppler effect?

Change in frequency due to a moving source of waves.

47

What is the human range of frequency?

20 Hz - 20,000 Hz

48

What are ultrasonic waves?

Frequencies higher than 20, 000 Hz

49

What are infrasonic waves?

Frequencies lower than 20 Hz

50

What is the medium?

What the wave travels through. For ex, air, water, traintracks

51

What is a mechanical wave?

A wave that needs a medium. ex. sound

52

What is electromagnetic wave?

A wave that can travel through empty space. ex. light, radio, cells

53

What is the speed of a wave effected by?

The medium and type of wave.

54

For light, a red shift indicates that the light source is moving

a. toward you

b. away from you

B. AWAY FROM YOU

55

A positive ion (charged atom) has more

a. electrons than neutrons

b. electrons than protons

c. protons than electrons

d. protons than neutrons

c. protons than electrons

56

The electrical force between charges is strongest when the charges are

a. close together

b. far apart

c. the electric force is constant everywhere

a. closer together

57

Electric potential, measured in volts, is the ratio od electric energy to amount of electric

a. current

b. resistance

c. charge

d. voltage

c. charge

58

The current through a 10-ohm resistor connected to a 120 V power supply is

a. 1 A

b. 10 A

c. 12 A

d. 120 A

c. 12 A

59

A 10 ohm resistor has a 5A current in it. What is the voltage across the resistor?

a. 5 V

b. 10 v

c. 15 v

d. 20 v

e. 50 v

e. 50 v

60

Modern automobile headlights are connected in

a. parallel

b. series

a. parallel

61

The power used in a 4ohm resistor carrying 3 A is

36 W

62

What is the source of all waves?

Something that is ﻿Vibrating. ﻿ ﻿

63

What is amplitude?

The maximum displacement on either side of the equilibrium midpoint position

64

What is Frequency?

The number of waves per time

65

What is Period?

The time of one wave or cycle

66

What is a transverse wave? a longitudinal wave?

A transverse wave is a wave that goes up and down. Light waves are transverse.

A longitudinal wave is a wave that goes back and forth. Sound is longitudinal.

67

Air is a poor conductor of sound. What are the best conductors?

liquids and solids.

68

What is compression? What is rarefraction?

Compression is a pulse of compressed air that travels across the room

A rarefraction is when molecules move toward the source and cause a low pressure, which disturbs the waves in the room. ex, when you close a door and the open window shade flaps towards you.

69

Thunder is heard after...

we see a flash of lightning (All sounds in the same medium travel at the same speed, that's why it takes a while to hear it, regardless of the frequency.)

70

Sound travels faster in

a. warm air

b. cold air

a. warm air, the reason why is because the faster moving molecules in the warm air bump into one another more often and therefor can transmit a pulse in less time.

71

Do compressions and rarefractions in a sound wave travel in the same direction or in opposite directions from one another?

They travel in the same direction.

72

what is pitch?

The highness or lowness of a tone

73

What is inside every atom?

Postive and negative charges.

74

What is the fundamental quantity that underlies all electrical phenomenon ?

Electric charge. (Positive and negative)

75

What is the conservation of charge?

No electrons are created nor destroyed, electrons are simply transferred from one material to another.

76

If you scuff your feet while you walk across a rug, are you negatively or positively charged?

You have more electrons after you scuff your feet, so you are negatively charged (and the rug is positively charged)

77

What is Coulombs Law?

It is the relationship among electrical force, charge and distance. F = k q1 x q2 / d^2\if the charges are alike in sign then the force is repulsive, if the charges are unalike then the force is attractive.

78

To move the positive charge to the left requires ________ which will increase the __________.

work, potential energy

79

I = current, what is the unit.

Amp.

80

As distance increases, force

a. increases

b. decreases

b. decreases

81

For electric current to flow you need a difference in

a. speed

b. current

c. potential energy

d. kinetic energy

c. potential energy

82

How do you get electric current?

You need a circuit with a conducter and a difference in electric potential energy.

83

If the Voltage goes up the current goes

a. down

b. up

b. up

84

What is resistance?

Electrical friction.

85

As resistance goes up, current goes

a. up

b. down

b. down

86

What is the electrical unit for resistance?

Ω

87

What is Ohms law?

The relationship among the voltage, current and resistance. Ohm discovered that the current in a circuit is directly proportional to the voltage, and is inversely proportional to the resistance of the circuit. C = V / R

88

What skin has more Resistance, wet skin or dry skin? why?

Dry skin has a higher resistance with a low electrical current. Conversely, wet skin has a low resistance and high electrical current. That is why electrocution occurs more often when exposed to water.