OCR A-Level Physics A H556
Practical Skills in the Written Papers
The Practical Endorsement
Physical Quantities and Units
Making Measurements and Analysing Data
Nature of Quantities
Motion
Forces in Action
Work, Energy and Power
Materials
Newton’s Laws of Motion and Momentum
Charge and Current
Energy, Power and Resistance
Electrical Circuits
Waves
Quantum Physics
Thermal Physics
Oscillations
Gravitational Fields
Astrophysics and Cosmology
Capacitors
Electric Fields
Electromagnetism
Nuclear and Particle Physics
Astrophysics and Cosmology
The solar system and the birth of a star
- 5 things to know
- Papers 1, 2 and 3
Overview
Recall questions on solar systems, planets, planetary satellites, comets, galaxies and the universe, and how a star forms from an interstellar cloud through gravitational collapse, fusion and the balance of radiation and gas pressure.
What you need to know
Answer each one before you reveal it.
What constitutes a solar system?
Define a galaxy.
What is a planetary satellite?
What energy transformation occurs as a protostellar cloud collapses, and what effect does this have?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What constitutes a solar system?
Model answer
A solar system consists of a star together with all the planets, moons, asteroids, comets and other objects gravitationally bound to it.
- 2
Define a galaxy.
Model answer
A galaxy is a large system of stars, gas, dust and dark matter held together by gravity, typically containing billions of stars.
- 3
What is meant by the universe?
Model answer
The universe is the totality of all space, time, matter and energy, encompassing all galaxies and the space between them.
- 4
What materials are present in the interstellar cloud from which stars form?
Model answer
The interstellar cloud contains hydrogen and helium gas plus dust.
- 5
What causes an interstellar cloud to begin collapsing during star formation?
Model answer
Gravitational attraction between particles in the cloud causes it to collapse.
- 6
Why does the collapse of a star-forming cloud accelerate over time?
Model answer
As the cloud collapses, its density increases, which strengthens gravitational attraction and accelerates the collapse further.
Other ways to work this
The same content, four other ways.
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Six ways to work the same material.
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