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eassessment Flashcards

1
Q

what is a satellite

A

anything which orbits a planet

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2
Q

what r the two types of sattelites

A

artificial and natural

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3
Q

list the 8 planets in order

A

mercury, venus, earth, mars, jupiter, saturn, uranus, neptune

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4
Q

difference between asteroids and comets

A

asteroids made mostly of rock and metal, comets made mostly of ice and dust

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5
Q

differenc between gas and rocky planets

A

A gas giant planet is large enough that it retains a lot of hydrogen and helium. A rocky planet is one with a solid surface.

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6
Q

what is astronomical unit

A

One AU is the average distance between the Earth and the Sun, which is approximately 150 million kilometers or 93 million miles.

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7
Q

what is keplers first law

A

planets orbit sun in an ellipse with sun at one focus and nothing at the second focus

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8
Q

keplers 2nd law

A

a line segment joining a planet and the sun sweeps out equal areas during equal intervals of time

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9
Q

keplers 3rd law

A

the square of the orbital period of a planet is proportional to the cube of the semi major axis of its orbit

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10
Q

state newtons law of gravitation

A

every object in the universe attracts every other object with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

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11
Q

what is the universal gravitational constant

A

6.673* 10^-11

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12
Q

what is the astronomical base for a year

A

time for sun to make one revolution around the eart

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13
Q

what is a day in astronomical terms

A

the time it takes for earths rotation along its axis

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14
Q

what is a month astronomically

A

measure of time required by the moon to revolve once around the earth

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15
Q

what types of telescopes r used these days

A

reflecting

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16
Q

describe the life cycle of a star up to the formation of red giant/supergiant, nothing after

A

big cloud of dust and gas (nebula) -> attractive force of gravity pulled dust and gas together to create protostar -> as the protostar becomes bigger and attracts more gas and dust, the gravity also squeezes the protostar making it more dense so its temperature increases -> as the temperature and pressure increases, helium nuclei is formd in nuclear fusion, giving out huge amounts of energy to become a main sequence star -> the outward pressure of nuclear fusion is balanced by inward pressure causing a long stable period which can last for billions of years, at some point the sun will run out of hydrogen and wont be able to do nuclear fusion so the gravity turns it smaller until it can start nuclear fusion again -> this time however, it can form heavier elements up to iron and starts expanding again-> if it was small/medium initially it would form a red giant and if it was big initially it would form a red supergiant.

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17
Q

life cycle of red giant

A

after a short time, it becomes unstable and expels its outer layers leaving behind a hot dense solid core called white dwarf which does not do any nuclear fusion, over time it becomes cooler and darker and transitions into a black dwarf as it has no energy to emit light.

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18
Q

life cycle of a red supergiant

A

red super giant get brighter as more nuclear fusion occurs, after several cycles of expansion and contraction they explode in a supernova which forms elements heavier than iron and r ejected across the universe. If the star was very big it then becomes a neutron star with a dense core however if it was massive, it becomes a blackhole

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19
Q

what is a light year

A

A light-year is a measure of the distance that light travels in a vacuum in one Earth year, which is approximately 6 trillion miles

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20
Q

what is red shift

A

light waves get stretched as they make their way to earth

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21
Q

what does the big bang theory state

A

all the matter in the universe initially occupied a small amount of space which was dense and hot and then it exploded causing space to expand

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22
Q

what is a force

A

something that can change the shape, speed or direction of an object

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23
Q

give 3 examples of contact forces

A

pushing force, pulling forcem friction

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24
Q

give 2 examples of non contact forces

A

electromagnetic force, gravitational force

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25
what is mass
amount of matter inan object
26
what is the strength of grav on earth
10 m/s^2
27
frictional force formula
coefficient of friction * normal force
28
what does coefficient of friction refer to
amount of friction between 2 surfaces
29
stopping distance formula
thinking distance + braking distance
30
newtons 1st law
a resultant force is required to change the motion of an object
31
newtons 2nd law
if a non zero resultant force acts on an object, it will cause the object to accelerate, f = ma
32
what is inertia
the tendency for the motion of an object to remain unchanged.
33
what is equilibrium
when net force is 0
34
what is newtons 3rd law
when 2 objects interact with each other, the forces they exert on each other r equal and opposite
35
what is terminal velocity
the maximum velocity reached by a falling object when drag force equals the weight of the object
36
unit for moment of force
Nm
37
moment of force formula
force times distance
38
law of lever
f1 x d1= f2 x d2
39
momentum formula
mass x velocity
40
unit for momentum
kg m/s
41
WHAT IS THE law of conservation of energy
energy is never created or destroyed, it is only ever transferred between different forms and objects
42
what is kinetic energy
enegry that an object possesses due to its motion
43
what is gpe
energy an object has due to its position above the surface of the earth
44
gpe of moon
1.6
45
watt to j/s
1
46
what is power
the rate at which energy is transferred or work is done
47
power formula with energy
p = E/t
48
power formula with work
P = W/t
49
when is work done
when force is used to move an object by a certain distance
50
what is efficiency
proportion of energy supplied that is transferred into useful energy
51
efficiency formula
useful energy transferred/total energy transferred
52
what is hooked law
the force applied to a spring is directly proportional to its extension
53
hookes law formula
F = k X F
54
---- to a spring is equal to ------- in the spring
work done, elastic potential energy
55
what is elastic limit
the point where the force applied means hookes law no longer applies and the object may be inelastically deformed
56
work formula
force * displacement
57
spring constant formula
k = F/d
58
what is thermal energy of am object
energy stored as kinetic energy due to movement of particles
59
how to convert from kelvin to degrees celsius
add 273
60
what is absolute 0
-273 kelvin
61
what it temperature a measure of
avg. kinetic energy
62
what is heat
a form of thermal energy
63
what r the 3 types of heat transfer
conduction, convection radiation
64
where does conduction, convection and radiation happen
conduction in solids convection in fluids radiation in empty space
65
what is thermal conductivity
measure of an objects ability to transfer energy by conduction
66
what is a cycle of convection called
convection current
67
how to stop flow of thermal energy
use insulators which stop the free flow of fluids and dont allow heat energy to pass thru
68
difference between conduction and convection
in conduction, only the energy is transferred while the particles actually move in convection
69
what is internal energy
total energy stored by the particles making up a substance or system consisting of potential and kinetic energy stores
70
what is specific heat capacity
amt. of energy needed to raise the temperature of 1 kg of a substance by 1 degree celsius.
71
change in internal energy formula
e = mc (change in temp.), e is change in internal energy, m is mass, c is specific heat capacity (j/kg)
72
y does temp not change during change of state
because the energy provided is being used to weaken or break the forces holding particles together
73
what is latent heat
the amt. of energy required to weaken or break the forces holding particles together
74
what is specific latent heat
energy required to change 1 kg of a particular substance from 1 state to another without changing its temp.
75
2 types of specific latent heat
slh of vaporisation, slh of fusion
76
formula for slh
e m * L, e is energy, m is mass, L is slh
77
list 4 good insulators
wood, plastic, paper
78
difference between longitudinal and transverse waves
longitudinal waves particles vibrate parallel to the direction of energy transfer transverse waves particle vibrate perpendicular to the direction of energy transfer
79
time period formula
1/f
80
speed of wave formula
frequency x wavelength
81
outline the meaning of loudness and of pitch in terms of features of a sound wave
greater amplitude, greater loudness. greater freqyency, greater pitch
82
what is speed of sound in air approc.
330-340 m/s
83
what is hearing range for humans
20 HZ TO 20 KHZ
84
what is ultrasound
ound with a frequency greater than 20,000 Hz, approximately the upper limit of human hearing.
85
list all 7 parts of the em waves from highest to lowest wavelength
radio waves. micro waves, infrared, visible light, ultra violet, xrays, gamma rays
86
what type of waves r em waves
transverse
87
speed of em waves in vacuum
3 * 10^8 m/s
88
where do gamma rays come from
radioactive decay
89
where r x rays used
hospital
90
where can uv rays be used
water purification
91
what is viaible light used for
seeing
92
where can infrared waves be used
cooking
93
what r microwaves used for
satellite communication
94
what r radio waves used for
communication on earth
95
what can gamma rays be used for
treatment of tumors
96
which parts of the em spectrum can cause burns to skin and also cause cancer by mutating the DNA inside cells
gamma rays and x rays as they r ionizing
97
list a harmful effect of uv rays
it can negatively affect the eyes
98
list an harmful effect of infrared rays
it can cause skin burns
99
what can happen to a wave once it strikes a medium
it can be absorbed, reflected or transmitted
100
law of reflection
angle of incidence = angle of reflection
101
tw0 types of reflection
specular- flat boundary diffuse- rough surface
102
what causes refraction
change in speed of light at a boundary
103
what happens to rays in more dense materials
it moves towards the normal
104
law of refraction
angle of incidence = angle of refraction
105
refractive index formula
speed of light in vaccum/speed of light in material
106
snells law
n1 sin1 = n2 sin 2
107
what is total internal reflection
complete reflection of a ray of light within a medium such as water or glass from the surrounding surfaces back into the medium.
108
what is critical angle
The critical angle is the angle of incidence that produces a 90 degrees angle of refraction.
109
snells law with critical angle
sin critical angle = 1/refractive index of material
110
what is diffaction
when waves bend passing thru a gap or an obstacle
111
characteristics of a plane mirror
virtual, erect, and of the same size and shape as the object it is reflecting.
112
two types of lenses
convex, concave
113
differnece betwene convez and concave lenses
convex lenses reflect rays inwards and concave refracts light outwards
114
magnification formula
image height/object height
115
where r convex lens used
microsocpes, magnifying glass
116
where r concave lens used
cameras
117
difference between rela image and virtual image
in real images, light rays do actually come together, it is vertically inverted, in virtual image, light rays dont actually meet where the image appears to be.
118
lens formula
1/image distance + 1/object distance = 1/focal length
119
list 4 ways to increase strength of magnetic field flowing thru solenoid
increase current flowing thru increase no. of coils decrease the length of coils while keeping no. of coils same add an iron core as iron is a soft magnet
120
flemings lhr
first finger is direction of magnetic field second finger is direction of current thumb is then direction of force
121
what does electromagnetic induction mean
a voltage is induced in a conducting wire when it moves relative to a magnetic field
122
force on wire between magnets formula
force = magnetic flux density * current * length of wire
123
how do transformers work briefly
power station -> step up transformer (more turns on coil so more voltage) ->wires and pylons-> step down transformers (less coils, less voltage)
124
transformer formulas (2)
Vp/Vs = np/ns Vp * Ip = Vs * Is
125
state 2 uses of static electricity
insecticides photocopier
126
what is the direction of conventional current
positive to negative
127
current formula
I = change in charge/time
128
voltage formula with energy
energy transferred/charge moved
129
what is resistance
tendency of a material to resist the flow of electric charge, unit is ohm
130
what is voltage
difference in potential energy between two points
131
ohms lae formula
V = I * R
132
resistance formula with factors
(resistivity * length)/cross-sectional area
133
series circuit formulas
I = I1 = I2 = I3, V = V1 + V2 + V3, R = R1 + R2 + R3
134
parallel circuit formulas
I = I1 + I2 + I3, V = V1 = V2 = V3, 1/R = 1/R1 + 1/ R2 + 1/R3
135
give an example of ac
residential power and commercial power
136
give an example of dc
computer power supply
137
power formula in electricity
P = IV
138
Power formula
P = work done/time
139
unit of payign electricity
kilowatt-hour
140
what r the dangers of current electricity
contact with voltage can cause current to flow thru body which can result in shocks, burns and even death.
141
what r the three wires in a plug with colors
live wire(brown), neutral(blue), earth (yellow and green)
142
what does live wire do
provides the alternating potential difference
143
what does neutral wire do
carries away current
144
what does the earth wire do
stops the casing from becoming live which could happen if live wire becomes loose and touches the casing. It prevents this by providing an alternative pathway for current to flow away.
145
how does a fuse work
if theres a surge, the fuse in the live wire melts due to the heat so no more current can flow thru it
146
how does a circuit breaker work
work similarly to fuses but dont get permanently damaged, they just turn off the circuit and can be reset
147
how does double insulating work
an appliance has a plastic casing which doesnt conduct electricity
148
how to increase potential difference in em induction
stronger magnets, move magnets or wire more quickly, more turns in coil
149
what r alpha particles stopped by
single sheet of paper
150
most ionising particles in order
alpha, beta, gamma
151
what stops beta
5 mm aluminium
152
what stops gamma rays
thick sheets of lead
153
what does alpha decay do
removes 2 protons and 2 neutrons
154
what does beta decay do
aotmic number increases by 1
155
name a tool to measure radioactivity and its unit
geiger muller detector, radioactive particles per second (count rate)
156
what is a use of gamma radiation
it is used in radiotherapy to kill cancer cells
157
what is a use of beta radiation
tracers injected into a body and followed using specialized equipment, cause they can pass thru a body like gamma.
158
what is a use of alpha radiation
smoke detectors
159
what type of radiation is used for sterilization
gamma
160
what is irradiation
the process by which objects r exposed to radiation
161
what is contamination
when radioactive particles get onto other objects
162
list 3 factors affecting how harmful radiation is
type of radiaiton where ur exposed to it the amount

physics (2 decks)

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