things to memorise Flashcards

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1
Q

Estimate the mass of a person

A

70kg

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2
Q

Estimate the height of a person

A

150cm

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3
Q

Estimate the walking speed of a person

A

1 m/s

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4
Q

Estimate the speed of a car on the motorway

A

30 m/s

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5
Q

Estimate the volume of a can of a drink

A

300 cm^3

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6
Q

Estimate the density of water

A

1000 kg/m^3

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7
Q

Estimate the current in a domestic appliance

A

13A

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8
Q

Estimate the e.m.f. of a car battery

A

12V

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9
Q

Estimate the hearing range (frequency)

A

20Hz to 20000 Hz

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10
Q

Estimate the young modulus of a material

A

something x 10^11

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11
Q

Distance

A

Total length moved (no direction)

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12
Q

Displacement

A

Distance in a certain direction

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13
Q

Speed

A

Distance over time taken

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14
Q

Velocity

A

Displacement over time taken

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15
Q

SUVAT Equations?

A
v=u + at
v^2= u^2 + 2as
s=ut + 1/2at^2
s=vt - 1/2at^2
s = 1/2(v + u) x t
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16
Q

Acceleration of free fall

A

9.81 m/s^-2

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17
Q

Projectile motion

A

uniform velocity in one direction and constant acceleration in perpendicular direction

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18
Q

Newton’s first law

A

An object remains stationary or in uniform motion unless a resultant force acts upon it.

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19
Q

Newton’s second law

A

The rate of change of momentum is proportional to the resultant force and occurs in the direction of force.

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20
Q

Newton’s third law

A

Every force has an equal force that occurs in the opposite reaction forming an action - reaction pair

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21
Q

Mass

A

Measure of the amount of matter in the body

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22
Q

Weight

A

Force of gravitational attraction on a body

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23
Q

Momentum

A

mass x velocity

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24
Q

Force

A

m x a; change in momentum/time taken for change

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25
Q

Principal of conservation of momentum

A

When bodies in a system interact, total momentum remains constant provided no external force acts on the system.

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26
Q

Perfectly elastic collision

A

A collision in which the total momentum is conserved. A collision in which the total kinetic energy is conserved.

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27
Q

Two identical spheres collide elastically. Initially, X is moving with speed v and Y is stationary. What happens after the collision?

A

X stops and Y moves with the speed of V : relative velocity before collision = - (relative velocity after collision)

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28
Q

Perfectly inelastic collision

A

Total energy is conserved but Ek is converted into other forms of energy. Only momentum is conserved and the particles stick together after collision.

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29
Q

Force

A

rate of change of momentum

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30
Q

Density

A

Mass per unit of volume

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31
Q

Pressure

A

Force per unit area

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32
Q

Upthrust

A

An upward force exerted by a fluid on a floating or submerged object. Caused by the difference in pressure on the bottom surface and the top surface.

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33
Q

Frictional force

A

Force caused by the rubbing of two surfaces

  • always opposes relative or attempted motion
  • always acts along the surface
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34
Q

Viscous force

A

Force caused by motion of an object in a fluid

  • only exists when there is motion
  • magnitude increases with speed of the object
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35
Q

Centre of Gravity

A

Theoretical point through which all the weight of an object is assumed to act.

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36
Q

Couple

A

A pair of forces the same size that produce rotation

  • same magnitude
  • same distance from pivot
  • opposite direction
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37
Q

Moment

A

Moment = force x distance from pivot (perp.)

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38
Q

Torque of a couple

A

Force x distance between forces

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39
Q

Conditions of equilibrium

A

Resultant force equals zero. Resultant rotational force (torque) is equal to zero.

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40
Q

Principle of moments

A

For a body to be in equilibrium, the sum of all clockwise moments must equal the sum of all anticlockwise moments about the same pivot.

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41
Q

Pressure in fluids

A

Volume of water = A x h
Mass of Water = density x volume = p x A x h
Weight of water = density x volume x gravitational force = p x A x h x g
Pressure = force/area = p x A x h x g/ A = p x g x h
Therefore pressure = pgh

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42
Q

Law of conservation of energy

A

The total energy of an isolated system cannot change - it is conserved over time. Energy cannot be made or lost just converted between different forms.

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43
Q

Work done by a force

A

W = F x s

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44
Q

Work done by an expanding gas

A

W = pressure x change in volume

Temperature of gas has to be constant.

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45
Q

Gravitational potential energy

A

W = m g h

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46
Q

Power

A

V x I; Work done / time taken

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47
Q

Efficiency

A

Useful energy output/total energy output x 100

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48
Q

Hooke’s Law

A

The extension produced by a spring is proportional to the applied force as long as the elastic limit is not exceeded: F = k x x

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49
Q

Parallel springs

A

ke = k1 + k2

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50
Q

Springs in series

A

1/ke = 1/k1 + 1/k2

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51
Q

Stress

A

Stress = Force / Cross-sectional area ( Pa)

52
Q

Strain

A

Extension / original length ( no units )

53
Q

Young Modulus

A

ration of stress to strain; units in Pa or N/m^2

54
Q

Elastic deformation

A

When deforming forces removed, the subject returns to original form

55
Q

Plastic deformation

A

When deforming forces removed, the subject returns to a stretched form

56
Q

Strain energy

A

The potential energy stored by an object when it is deformed elastically W=1/2kx^2

57
Q

Displacement (wave)

A

Distance of a point from its undisturbed position

58
Q

Amplitude

A

The maximum displacement of a wave

59
Q

Period

A

The time taken for 1 complete oscillation to occur

60
Q

Frequency

A

Number of oscillations past a point per unit time

61
Q

Wavelength

A

Distance from any point on the wave to the next exactly similar point

62
Q

Wave speed

A

Speed at which the waveform travels in the direction of the propagation of the wave

63
Q

Progressive waves

A

Transfer energy from one position to antoerh

64
Q

Wave equation

A

v = lambda/ time and time= 1/f therefore v = lamba x frequency

65
Q

Phase difference

A

Phase difference between two waves is the difference in terms of fraction of a cycle or in terms of angles.

66
Q

Intensity

A

Power / Area; intensity is proportional to amplitude squared

67
Q

Transverse waves

A

Waves in which the oscillations occur at 90 degrees to the direction of propagation.

68
Q

Longitudinal waves

A

Waves in which the oscillations of the wave are parallel to the direction of propagation

69
Q

Doppler effect

A

Observed freqeuncy = Frequency of source ( velocity of source wave / velocitiy of source wave (+-) velocity of source)

70
Q

Electromagnetic waves

A

All travel at the speed of light : 3 x 10^8
Travel in free space ( no medium )
Can transfer energy
Transverse waves

71
Q

What is the frequency of radio waves?

A

10^3

72
Q

What is the frequency of microwaves?

A

10^-2

73
Q

What is the frequency of infrared

A

10^-5

74
Q

What is the frequency of visible light

A

0.5x10^-6

75
Q

What is the frequency of ultraviolet waves?

A

10^-8

76
Q

What is the frequency of X-ray?

A

10^-10

77
Q

What is frequency of gamma ray?

A

10^-12

78
Q

Interference

A

The formation of poitns of cancellation and reinforcement where 2 coherent waves pass each other

79
Q

Coherence

A

waves having constant phase difference

80
Q

Stationary wave

A

A stationary wave is formed when two progressive waves of the same frequency, amplitude and speed that are travelling in opposite directions superpose. Stationary waves store energy.

81
Q

Node

A

Region of destructive superposition

82
Q

Antinode

A

Region of maximum constructive superposition

83
Q

Diffraction

A

The spreading of waves as they pass through a narrow slit

84
Q

What is the equation for double slit interference?

A
lambda = ax/D
a = split separation
x = width of gap
D = distance from slit to screen
85
Q

What is the equation for diffraction grating?

A
d sin (theta) = n x lambda
d= distance between successive slits
  = reciprocal of number of lines per meter
theta = angle from horizontal equilibrium 
n= order number
86
Q

What happens to a positive charge in an electric field?

A

Positive charge moves in the direction of the electric field; they gain Ek and lose Ep

87
Q

What happens to a negative charge in an electric field?

A

Negative charge moves in opposite direction of the electric field: they lose Ek and gain Ep

88
Q

Electric field strength

A

Force per unit of charge acting at a point. F/q or V/d
F is the force and q is the charge
V is p.d. and d is distance between parallel plates

89
Q

Electric current

A

Flow of charged particles

90
Q

Charge

A

Product of the current at that point and the time for which the current flows Q= I x t

91
Q

Coulomb

A

Charge flowing per second pas a point at which the current is one ampere

92
Q

Potential difference

A

The work required to move a certain coulomb of charge between two points.

93
Q

Power

A

I x V

94
Q

Ohm’s law

A

V = IR

95
Q

Current carrying conductors - formula?

A
I = (nLAq) / (L/v) 
L = length of conductor
A = cross-sectional area of conductor 
n = no. of free electrons per unit volume
q = charge on one electron 
v = average electron drift velocity
96
Q

What is the relationship between I and V for a metallic conductor?

A

Linear - V is proportional to I

97
Q

What is the relationship between I and V for a filament lamp?

A

As volts go up the temperature goes up. This increases the vibration of ions, increasing the collisions of ions with electrons. This increases resistance. Straight line then curves off at the top

98
Q

What is the relationship between I and V for a thermistor

A

As the voltage goes up, the temperature goes up. This releases electrons reducing resistance. Resistance which is V/I increases. Starts off straight and gradient gets steeper and steeper

99
Q

What is the relationship between I and V for a diode

A

Low resistance in one direction and infinite resistance to the left of the origin - I = 0

100
Q

Resistivity

A

R = pL/A

101
Q

e.m.f.

A

The energy converted into electrical energy from other forms when a current passes through the power source.

102
Q

Internal resistance

A
Resistance to current flow within the power source. 
Voltage across resistor = V= IR
Voltage lost to internal resistance V=Ir
Therefore e.m.f. 
E= IR + Ir
E= I(R + r)
103
Q

Kirchhoff’s second law

A

The sum of emfs in a closed circuit is equal to the sum of potential differences.

104
Q

Kirchhoff’s first law

A

The sum of currents entering a junction is equal to the total sum of currents leaving a junction

105
Q

Thermistor

A

A type of potential divider. Resistance decreases with increasing temperature.

106
Q

Light Dependent resistor

A

Resistance decreases with increasing light intensity.

107
Q

Potentiometer

A

A continuosly variable potential divider used to compare potential differences. Potential difference along the wire is proportional to the length of the wire.

108
Q

What are the results of Rutherford’s gold scattering experiment?

A

A beam of alpha particles were fired at a thin gold foil:
- most particles pass straight through
- some are scattered slightly
- very few deflect at an angle greater than 90
Conclusion:
- All mass and charge concentrated in the centre of the atom
Nucleus is positively charged as a-particles are repelled

109
Q

Isotope

A

Atoms of the same element with a different number of neutrons but the same number of protons

110
Q

Random (radioactivity)

A

Impossible to predict and each nucleus has the same probability of decaying per unit time

111
Q

Spontaneous (radioactivity)

A

Not affected by external factors such as the presence of other nuclei, temperature and pressure

112
Q

Features of an alpha particle

A

-Helium nucleus
-42He (symbol)
+2 charge
4 relative mass
slow speed
penetration can be stopped by paper
highly ionizing
effect of magnetic field causes particle to deflect slightly
effect of electric field causes particle to attract to negative

113
Q

Features of a beta particle

A
two types - positron B+ and electron B-
0-1e 0+1e 
-1 charge and +1 charge
Fast movement speed
can be stopped by few mm of aluminium
low ionisation energy
deflected greater by magnetic field than alpha particles
attracted to opposite charge of the particle
114
Q

Features of gamma radiation

A
electromagnetic
no charge
no mass
speed of light
few cm of lead
very low ionisation power
unaffected by electric and magnetic fields
115
Q

a-decay

A

Loses a helium proton

116
Q

B- decay

A

Neutron turns into a proton and an electron. An electron (0-1e) and antineutrino (00v with a line over it) are emitted

117
Q

B+ decay

A

proton turns into a neutron and a positron. An electron and neutrino are emitted. neutrino shown by v with no line

118
Q

Gamma decay

A

A nucleus changes from a higher energy state to a lower energy state through the emission of electromagnetic radiation ( protons)

119
Q

Fundamental particle

A

a particle that cannot be split up into anything smaller

120
Q

Quarks

A

Quarks are fundamental particles that make up protons and neutrons.

121
Q

Up Quark charge?

A

u - +2/3

122
Q

Down Quark charge?

A

d -1/3

123
Q

Strange Quark charge?

A

s -1/3

124
Q

Antiparticle

A

All quarks have antiparticles. The charge is just the opposite

125
Q

Leptons

A

A part of elementary particles- electron family is part of this group. Electrons, positrons, antineutrinos and neutrinos

126
Q

Hadrons

A

Part of composite particles. Hadrons —> baryones —> protons and neutrons