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Physics > Energy and Space > Flashcards

Energy and Space Flashcards

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1
Q

What is energy?

A

Energy is the ability to do something
it is measured in Joules (J)

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2
Q

What are the 8 types of energy

A

Heat energy
Electrical energy
Light energy
Kinetic energy
Chemical energy
Gravitational potential energy
Sound energy
Nuclear energy

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3
Q

State the law of conversion of energy

A

Energy cannot be created or destroyed. It can only be transformed from one form to another.

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4
Q

How do we “lose” energy

A

The energy wasted. In many situations friction produces heat energy, this energy escapes to the air around us, it is not destroyed but we can’t get it back and it’s not useful to us.

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5
Q

What is the formula for work done?

A

Ew = Fd

Ew = Work done measured in Joules(J)
F = Force applied measured in newtons (N)
d = Distance measured in metres (m)

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6
Q

Explain gravitational potential energy

A

When you lift up a heavy box, you do work - you apply a force through a distance.

The word you do is stored in the box as gravitational potential energy. The heavier the box the more potential energy is stored. The higher you lift the box, the more potential energy is stored.

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7
Q

What is the formula for Gravitational potential energy

A

Ep = mgh

Ep = Gravitational potential energy measured in joules (J)
m = mass of object measured in kilograms (kg)
g = gravitational field strength measured in newtons per kilogram (Nkg^-1)
h= height measured in metres (m)

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8
Q

What is the gravitational field strength on earth

A

9.8 Nkg^-1

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9
Q

What is kinetic energy

A

Anything that moves has kinetic energy. The heaveir the object the more kinetic energy. The faster the object is moving the more kinetic energy it has.

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10
Q

Formula for kinetic energy?

A

Ek = 1/2mv^2

Ek= kinetic energy measured in Joules (J)
m = mass measured in kilograms (kg)
v = speed measured in metres per second (ms^-1)

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11
Q

Explain the law of conversion for kinetic energy and work done

A

When a moving object is stopped it loses all of its kinetic energy. The force of friction does work on the object turning the kinetic energy into heat energy.

Ek = Ew

1/2mv^2 = Fd

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12
Q

What is a projectile?

A

A projectile is something that moves unde rthe influence of gravity and no other forces.

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12
Q

Explain the law of conversion for kinetic energy and potential energy.

A

if something falls it loses its potential energy because its losing height it gains kinetic energy because its travelling faster and faster. by the time the object hits the ground its potential energy has all converted to kinetic energy.

Whenever an object rises or falls:
gain/loss in kinetic energy = loss/gain in potential energy

Ek = Ep

1/2mv^2 = mgh

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13
Q

What path do projectile follow

A

curved path

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14
Q

Why do projectiles follow a curved path?

A

The projectile moves at a constant speed horizontally and is constantly accelerating vertically. This creates a curved path.

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15
Q

How do you calculate distance in projectile calculations

A

create a speed time graph

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16
Q

What is a satellite?

A

A satellite is anything that orbits another body, such as the earth.

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17
Q

What is an example of a natural satellite

A

The moon

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18
Q

Name 3 examples of artificial satellites

A

The ISS
Communication satellite
Weather satellite
GPS satellites
Hubble space telescope

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19
Q

How does a satellite stay in orbit.

A

Its horizontal speed is very high.

The weight of the satallite is making it accelerate towards the earth and its horizontal speed is constant. however the horizontal speed is so high that the curve of the fall matches the curve of the earth.

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20
Q

What is the period of a satellite

A

The time it takes a satellite to complete one orbit.

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21
Q

What does the period of a satellite depend on?

A

Its altitude. the greater the altitude of the orbit, the greater the period of the satellite.

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22
Q

What is a geostationary satellite?

A

A satelite that stays over the same geographical location throughout its whole orbit.

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23
Q

What are the properties of a geostationary satellite?

A

They have a period of 24 hours and an altitude of 36000km

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24
Q

Why might you use a geostationary satellite

A

they are useful if we want to communicate with the satellite at all times.

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25
Q

What are some common purposes of satellites

A

Communication
Weather forecasting
GPS
astronomy research

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26
Q

What makes getting into space difficult

A

The Earths gravitaional field.

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27
Q

How does a rocket take off

A

When a rocket takes off from the launch pad there are two forces acting - its weight downwards and the thrust from the rocket engines upwards.

If the thrust is bigger than the weight there will be an unbalanced force upwards. Newton’s second law tells us that this will cause the rocket to accelerate.

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28
Q

Why would we want to build rockets on the moon to launch?

A

The moons gravitational field is much lower than the earths meaning less thrust is needed to launch the rocket therefore meaning less fuel and therefore it is cheaper.

29
Q

How does a rocket move in space?

A

The rocket engines apply a force to the gases and the gases apply a force to the rocket. This reaction force makes the rocket accelerate.

30
Q

Describe an Ion drive

A

An ion drive contains a gas called xenon. The xenon atoms are ionised and become positively charged due to the loss of elctrons. There is also a thin sheet of metal with many little holes in it. This metal is negatively charged so attracts the xenon ions. These ions are moving very fast so they zoom through the holes and out the other side of the metal screen. As they shoot out (action) they push back against the spacecraft (reaction) causing it to accelerate

31
Q

How can we travel large distances in space

A

Ion drives
Gravitational asssists - “slingshot” effect

both of these increase speed.

32
Q

Describe gravitation assists.

A

This is when we use the gravitational field of a fast moving asteroid, a moon or a planet to increase the speed of the aircraft without using any fuel. as the spacecraft passes close to the object it picks up speed and keeps it as it moves away.

The energy is “borrowed” from the planet for a short period of time.

33
Q

Why do we not need to use the engines once a rocket has reached the right speed?

A

There is no friction in space so it will continue to move at a constant speed.

34
Q

Why do rockets require energy during long trips.

A

To keep life support systems running

35
Q

How can we supply energy to rockets

A

Solar panels if the spacecraft is reasonably close to the sun

Nuclear reactor if the spacecraft is getting further away from the sun.

36
Q

Name the key risks associated with space travel

A

Fuel load on take off
Potential exposure to radiation
Pressure differential
Re entry through an atmosphere

37
Q

Describe the fuel load on take off risk of space travel

A

Rocket fuel is dangerous - it is designed to burn

When a rocket is taking off it has a huge fuel load. If its not properly controlled it can have devastating consequences.

gases in the external fuel tank could mix explode and tear the space shuttle apart.

38
Q

Describe the potential exposure to radiation risk of space travel

A

The earths atmosphere protects us from ionising radiation that is in space including gamma radiations.

Astronauts in space don’t have this. Long term exposure to radiation could increase the chance of developing cancer.

In labs we use lead shielding to protect ourseleves however this would work for spacecrafts as it is too heavy.

39
Q

Describe the pressure differential risk of space travel.

A

Space is a vaccum where there is no air pressure.

A spacecraft has normal air pressure so astronauts can breathe.

This means there is a big pressure difference between the two, if something were to damage the aircraft, even a small hole would cause the spacecraft to blow apart due to the sudden change in pressure. This is called sudden decompression.

40
Q

Describe the re entry through an atmosphere risk of space travel.

A

A spacecraft re enters the earths atmosphere at a very high speed. Because of this it must hit the atmospher at the right angle - between 5 and 8 degrees.

if it hits at too low an angle it will “bounce” off the atmosphere and it likely won’t have enough fuel to turn back.

If it hits at too big angle the heat caused by friction with the atmosphere will be so great it will destroy the spacecraft.

41
Q

What is a light year

A

a light year is a unit of distance. It is the distance travelled by light in one year.

42
Q

How big is a light year in metres?

A

9.46 x 10^15 metres

43
Q

What is the speed of light

A

3x10^8

44
Q

Define a planet

A

A large object that orbits a star

45
Q

Define a dwarf planet

A

A small object that orbits a star

46
Q

Define a moon

A

A natural satellite of a planet

47
Q

Define the sun

A

The star at the centre of our solar system

48
Q

Define an asteroid.

A

A small, rocky body that orbits the sun made from materials left over from when the planets formed

49
Q

Define a solar system

A

Our sun and all the objects that orbit it due to gravity.

50
Q

Define a star

A

A huge bright ball of burning gases that is held together by gravity.

51
Q

Define an exoplanet

A

A planet that orbits a star in another solar system

52
Q

Define a galaxy

A

A vast collection of stars,gas and dust.

53
Q

Define the universe

A

Everything that exists including planets, stars, galaxies and all forms of matter and energy.

54
Q

How old is the universe

A

13.8 billion years

13.8 x 10^9 years old

55
Q

How do we know the age of the universe

A

The universe is still expanding, everything is getting further away from each other. If they are moving further away they must have all previously been quite close together which means at some point all galaxies were at the same point.

When galaxies move further away from us the light we receive is “redder” than it should be this is called red shift.

If we measure the amount of red shift we can find the speed of the galaxies, if we know the how far away they are and their speed we can figure out how long they have been moving for. This is the age of the universe.

56
Q

What was before the big bang?

A

Nothing. The question is flawed. Time, space and matter all began with the big bang. There was no time and therefore not a “before”

57
Q

What is the order of events of the creation of the universe

A

1) Big bang
2) Four fundamental forces act as one
3) Seperation of the fundamental forces
4) Porotns and neutrons form
5) Electrons form
6) Protons and neutrons combine into nuclei
7) Appearance of atoms
8) First stars begin to form
9) Formation of the milky way galaxy
10) Creation of our solar system
11) Dust forms the planets

58
Q

What parts of the electromagnetic spectrum penotrate earths atmosphere

A

Visible light and radio waves

Partly penotrate:
Infrared, microwaves and tiny amounts of UV.

59
Q

What types of telescopes can be based on earth and why?

A

Visible light and radio wave telescopes. These wavelengths penotrate earths atmosphere and can be detected at ground level.

60
Q

Why would x ray telescopes need to be placed in space?

A

The atmosphere absorbs X rays

61
Q

Describe how we detect signals from space

A

Radio waves can be detected by an aerial or a receiver however the radio waves are very weak. To solve this issue we make curved reflectors that are either as large as possible or put together in an array. These receivers are called radio telescopes. They do the same job as other telescopes but they “look at” radio waves.

62
Q

Why would a visible light telescope be placed into space

A

To get clearer pictures

63
Q

What information can we gather by looking at the emissions (em spectrum parts) of a star.

A

Temperature mass size and composition

64
Q

What is visible light analysed by?

A

Spectroscopes

65
Q

Which colour of light refracts the least?

A

Red

66
Q

Does red light have a long or short wavelength

A

Long

67
Q

Which colour of light refracts the most

A

Violet

68
Q

Does violet light have a long or short wavelength

A

Short

69
Q

What is line spectra?

A

When an electrical current is passed through a gas or if the gas is very hot energy is emitted in the form of light. If we pass that light through a diffraction grating we see lines of different colours. Only certain frequencies(colours) of light are produced - the actual frequencies depend on the element that makes up the gas.

Each element produces a unique pattern of coloured lines called a line spectrum. It’s as though each element has its own “fingerprint”

so if we look at the line sopectra we get from starlight we can tell which elements the star is made from.

70
Q

How do you tell how much of an element there is in a line spectrum?

A

By measuring the intensity (brightness) of each wavelength (colour) of light derecred. The more of an element the more intense the wavelength of the element will be.

71
Q
A

Physics (7 decks)

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