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Physics 1 Flashcards

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1
Q

What is a system in physics?

A

A system is an object or group of objects. When a system changes, energy is transferred into or away from it, between objects in the system, or between different energy stores.

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2
Q

What are energy stores?

A

Energy can be stored in different ways, such as kinetic, gravitational potential, elastic potential, chemical, thermal (internal), and nuclear stores.

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3
Q

What is kinetic energy?

A

Kinetic energy is the energy an object has due to its motion.

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4
Q

Kinetic energy formula

A

E_k = 0.5 × mass × (speed)^2 ; E_k = 1/2mv^2

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5
Q

What are the units for kinetic energy?

A

Kinetic energy is measured in Joules (J). Mass in kilograms (kg), speed in meters per second (m/s).

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6
Q

What is gravitational potential energy (GPE)?

A

GPE is the energy stored by raising an object above ground level.

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7
Q

Gravitational potential energy formula

A

E_p = mass × gravitational field strength × height ; E_p = mgh

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8
Q

What are the units for GPE?

A

GPE is measured in Joules (J). Mass in kg, gravitational field strength in N/kg (usually 9.8 N/kg), height in meters (m).

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9
Q

What is elastic potential energy?

A

Elastic potential energy is the energy stored in a stretched or compressed spring.

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10
Q

Elastic potential energy formula

A

E_e = 0.5 × spring constant × (extension)^2 ; E_e = 1/2 ke^2

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11
Q

What are the units for elastic potential energy?

A

Elastic potential energy is measured in Joules (J). Spring constant in N/m, extension in meters (m).

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12
Q

What is specific heat capacity?

A

Specific heat capacity is the amount of energy required to raise the temperature of one kilogram of a substance by one degree Celsius.

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13
Q

Specific heat capacity formula

A

Change in thermal energy = mass × specific heat capacity × temperature change ; ΔE = mcΔθ

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14
Q

What are the units for specific heat capacity?

A

Joules (J) for energy, kilograms (kg) for mass, J/kg°C for specific heat capacity, and °C for temperature change.

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15
Q

What is internal energy?

A

Internal energy is the total kinetic and potential energy of the particles in a system.

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16
Q

How does heating change internal energy?

A

Heating increases the internal energy by increasing the kinetic energy of the particles.

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17
Q

What is power?

A

Power is the rate at which energy is transferred or work is done.

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18
Q

Power formula

A

P = E / t or P = W / t ; P = power (W), E or W = energy transferred or work done (J), t = time (s)

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19
Q

What is efficiency?

A

Efficiency tells us how much of the input energy is usefully transferred.

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20
Q

Efficiency formula

A

Efficiency = (useful energy output / total energy input) × 100

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21
Q

How can efficiency be calculated with power?

A

Efficiency = (useful power output / total power input) × 100

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22
Q

What is a Sankey diagram?

A

A Sankey diagram shows how input energy is split into useful energy and wasted energy.

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23
Q

What is dissipation of energy?

A

Dissipation is when energy is spread out to the surroundings and is no longer useful.

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24
Q

What is meant by ‘wasted energy’?

A

Wasted energy is energy that is not usefully transferred, often dissipated as heat, sound, or vibration.

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25
How does insulation reduce unwanted energy transfer?
Insulation reduces the amount of heat lost to the surroundings by trapping heat and slowing its transfer.
26
What does thermal conductivity mean?
Thermal conductivity is how easily heat can pass through a material. Materials with low thermal conductivity (insulators) reduce energy transfer by heating.
27
What are renewable energy resources?
Renewable energy resources can be replenished and will not run out (e.g., wind, solar, hydroelectric, biofuel, geothermal, tidal, water waves).
28
What are non-renewable energy resources?
Non-renewable energy resources will eventually run out (e.g., coal, oil, gas, nuclear fuel).
29
Give examples of main uses for energy resources.
Transport, electricity generation, and heating.
30
What are the environmental impacts of burning fossil fuels?
Burning fossil fuels releases greenhouse gases (CO2), contributes to acid rain (SO2), and is non-renewable.
31
What are the main types of nuclear radiation?
Alpha (α), Beta (β), Gamma (γ)
32
What is alpha radiation?
Alpha is 2 protons and 2 neutrons (helium nucleus), strongly ionising, poorly penetrating (stopped by paper).
33
What is beta radiation?
Beta is a high-speed electron, moderately ionising, moderately penetrating (stopped by a few mm of aluminium).
34
What is gamma radiation?
Gamma is electromagnetic radiation, weakly ionising, highly penetrating (stopped by thick lead or concrete).
35
How do you represent alpha decay in nuclear equations?
Alpha decay: mass number decreases by 4, atomic number decreases by 2. E.g., 238/92U → 234/90Th + α
36
How do you represent beta decay in nuclear equations?
Beta decay: mass number stays the same, atomic number increases by 1 (neutron becomes a proton and emits an electron).
37
What is half-life?
Half-life is the time it takes for the activity or number of unstable nuclei in a sample to halve.
38
How do you calculate remaining activity after several half-lives?
Remaining activity = Initial activity × (1/2)^n ; n = number of half-lives elapsed
39
What are sources of background radiation?
Cosmic rays, radon gas, rocks, medical sources, food.
40
What are some uses of nuclear radiation?
Smoke alarms (alpha), medical tracers (gamma), thickness control in industry (beta).
41
What is meant by radioactive contamination?
Radioactive contamination is the unwanted presence of radioactive materials on other objects.
42
What is irradiation?
Irradiation is exposure to radiation, but does not make objects radioactive.
43
How do you protect against radioactive hazards?
Use shielding, limit time of exposure, handle sources with tongs, keep sources in lead containers.
44
What is the structure of an atom?
Atoms have a nucleus made of protons and neutrons, surrounded by electrons.
45
What is an isotope?
Isotopes are atoms of the same element with different numbers of neutrons.
46
What charge do protons, neutrons, and electrons have?
Proton: +1, Neutron: 0, Electron: -1
47
What is the mass number of an atom?
Mass number = number of protons + number of neutrons
48
What is the atomic number of an atom?
Atomic number = number of protons
49
What was the Plum Pudding Model?
The Plum Pudding Model described the atom as a sphere of positive charge with electrons embedded in it.
50
What did Rutherford’s gold foil experiment show?
Most alpha particles passed through gold foil, some were deflected, and a few bounced back, showing atoms have a small, dense nucleus.
51
What did the Bohr model propose?
Bohr suggested electrons orbit the nucleus at set distances in energy levels.
52
What is nuclear decay?
Nuclear decay is when unstable atomic nuclei emit radiation to become more stable.
53
What is activity (in radioactivity)?
Activity is the rate at which a source of unstable nuclei decays, measured in becquerels (Bq).
54
What are the three main types of nuclear decay?
Alpha (α), Beta (β), and Gamma (γ)
55
Which type of radiation is most ionising?
Alpha radiation is the most ionising.
56
Which type of radiation is most penetrating?
Gamma radiation is the most penetrating.
57
What is meant by count rate?
Count rate is the number of decays recorded each second by a detector (e.g., Geiger-Muller tube).
58
What is the formula for energy transferred by heating (specific heat)?
ΔE = mcΔθ ; ΔE = change in thermal energy (J), m = mass (kg), c = specific heat capacity (J/kg°C), Δθ = change in temp (°C)
59
What are the units for power?
Power is measured in watts (W).
60
What does efficiency mean in an energy transfer?
It means how much of the energy supplied is usefully transferred.
61
What happens to the energy that is not transferred as light in a bulb?
It is dissipated (mainly as heat) to the surroundings.
62
What is an anomalous result?
An anomalous result is one that does not fit the pattern and should be investigated, not included in averages.
63
What is the difference between alternating current (a.c.) and direct current (d.c.)?
A.C. changes direction periodically, D.C. flows in one direction only.
64
How do you increase the efficiency of an energy transfer?
By reducing the amount of wasted energy (e.g., by lubrication, insulation).
65
What are the hazards of handling radioactive sources?
Risk of contamination or irradiation, so use tongs, shielding, and limit exposure time.
66
What is the difference between radioactive contamination and irradiation?
Contamination is when radioactive material is on or in an object; irradiation is exposure to radiation but without radioactive material remaining.
67
What is the half-life of a substance?
The time taken for the activity (or number of radioactive nuclei) to fall to half its original value.
68
How do you calculate the activity after a certain number of half-lives?
Final activity = Initial activity × (1/2)^n ; where n = number of half-lives
69
How is an isotope represented?
By its mass number (top) and atomic number (bottom), e.g., 14/6C
70
What are the units for half-life?
Usually measured in seconds, minutes, hours, or years, depending on the isotope.
71
What is meant by 'reproducible' in an experiment?
'Reproducible' means the experiment can be repeated with the same result by different people. Important for reliability of results.
72
What are the key words related to energy transfers?
system, energy, kinetic energy, gravitational potential energy (GPE), elastic energy, internal energy, specific heat capacity, transferred, dissipated, conductivity, renewable
73
Use a Sankey diagram to illustrate the energy changes involved when a diesel powered crane is used to lift an object.
Draw arrows showing input energy split into useful energy (lifting object) and wasted energy (e.g., sound, heat).
74
Work out the energy required to heat 1.5kg of water from 20°C to 100°C. (c = 4200J/kg°C)
Q = mcΔT = 1.5 × 4200 × (100-20) = 1.5 × 4200 × 80 = 504,000J
75
Explain what is meant by 'reproducible' and why it is important.
'Reproducible' means the experiment can be repeated with the same result by different people. Important for reliability of results.
76
A 20W light bulb transfers 15W usefully as light energy. What happens to the energy that is not transferred as light?
The other 5W is dissipated (mainly as heat) to the surroundings.
77
Describe one ethical consideration of hydroelectric power.
It can flood land and habitats, displacing people and wildlife, and affecting local environments.

Science-Physics 1 (3 decks)

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