Topic 10 - Space (GCSE Edexcel Physics Retrieval Questions)

What does our solar system consist of?

The Sun, eight planets, natural and artificial satellites, dwarf planets, asteroids and comets

Give an example of a natural satellite.

Moon

Give an example of an artificial satellite.

ISS

What's the difference between planets and dwarf planets?

The gravitational field around planets is strong enough to have pulled in all nearby objects with the exception of natural satellites

What is an asteroid?

An asteroid is a small rocky object which orbits the Sun

What is a comet?

Comets are made of dust and ice and orbit the Sun in a different orbit to those of planets.

What is the order of the planets, from closest to futherest from the sun?

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

How is mass of a planet related to its gravitational field strength?

The greater the mass of the planet then the greater its gravitational field strength

What is the difference between the geocentric and heliocentric models of the solar system?

Geocentric - the solar system had the Earth at the centre of it and Heliocentric - the solar system has the Sun at the centre of it.

What was the evidence for the geocentric model of the solar system?

Objects in the sky appear to move in the same direction and in a predictable pattern of movement which is the same each day

What was the evidence against the geocentric model of the solar system?

The moons of other planets (such as Jupiter) can clearly be seen to be orbiting the other planet and not the Earth and detailed telescope observations show the planets of the Solar System do not move in a simple orbital path around the Earth

"How can the force of gravity lead to changing velocity of a planet but unchanged speed?

Velocity is speed in a given direction. Whilst speed is constant, direction is always changing."

How are comet orbits different to planet orbits?

Their orbits are highly elliptical or hyperbolic. This causes the speed of the comets to change significantly as their distance from the Sun changes (higher nearest to the sun).

If the speed of the satellite is too large, what will happen?

The radius of the orbit will increase and the satellite will spiral into space due to lack of gravity.

If the speed of the satellite is too low, what will happen?

The radius of the orbit will decrease and the satellite will move towards the object it should be orbiting, due to too much gravity.

What powers stars?

Nuclear fusion

For thermal equilibrium in a star, what needs to be balanced?

Gravity inwards and outward force which is exerted from the expanding hot gases inside the star

What happens to a star if it's temperature increases?

Outward pressure increases and the star expands.

What is a nebula?

A giant cloud of hydrogen gas and dust

How does a protostar form?

The force of gravity within a nebula pulls the particles closer together until it forms a hot ball of gas. More frequent collisions causes an increase in temperature.

When does a protostar become a main sequence star?

When it is hot enough for fusion to start.

What size star will become a red giant, and what will it go on to become after?

<8 time the mass of our sun, will g0 on to become white dwarf and then a black dwarf

Why does a main sequence star become a red giant?

It runs out of fuel for fusion, outward pressure decreases and gravity shrinks the star. More collisions then cause a heat spike and the star expands.

Why does a red giant become a white dwarf?

It ejects outer layer as planetary nebula, the core left behind collapses and heats up due to collisions.

Why is a black dwarf theoretical?

Because the emit no light or heat so they are hard to detect and because they take longer than 14 billion years to form (the age of the universe).

What size star will become a super red giant, and what will it go on to become after?

>8 times the mass of our sun, will become a supernova then either a neutron star (<25 solar masses) or black hole (>25 solar massed)

What element do red super giants stop fusing after and why?

Iron because afterwards it will take energy to fuse elements.

What is a supernova?

Sudden collapse of a red super giant which then explodes and ejects remnants into space?

Why do we have elements with higher atomic masses than iron?

Steller nucleosynthesis - heat and pressure from fusion forces iron and other elements together.

What is a neutron star?

The dense remnants of a supernova.

Why do super massive stars become black holes and what are they?

The core continues to collapse due to gravity and becomes an extremely dense point which light cannot escape.

What is the doppler effect?

A moving object will cause the wavelength, λ, (and frequency) of the waves to change.

If an object moves towards an observer, how will waves appear compared to when they are stationary?

The wavelength of the waves in front of the source decreases (λ - Δλ) and the frequency increases

Describe red shift.

An object moves away from an observer the wavelength of light increases, shifting it towards the red end of the spectrum.

Describe blue shift.

An object moves towards an observer the wavelength of light decreases, shifting it towards the blue end of the spectrum.

What does red shift from galaxies in our universe indicate?

That galaxies are moving away from us.

Why do light spectrums produced from distant galaxies red-shift more than nearby galaxies?

Because the futher away galaxies are moving away from us at a faster velocity than closer galaxies.

What is the steady state theory?

The Universe has always existed, and that the Universe is expanding and constantly creating matter as it expands.

What is the big bang theory?

About 13.8 billion years ago all the matter in the Universe was concentrated into a single incredibly tiny point. From this tiny point, the whole Universe expanded outwards.

What is CMBR (Cosmic Microwave Background Radiation)?

EM radiation detected from all directions at the same temperature. Gamma rays that have been stretched over time due to the universe expanding, the wavelength has increased to be in the microwave region.

Does red shift explain the steady state theory and/or the big bang theory and why?

Yes, because both theories suggest that the universe is expanding.

Does CMBR explain the steady state theory or the big bang theory and why?

Big bang theory because CMBR suggests that the universe has a starting point and time.