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CHAPTER 14 REVIEW 1a) False. Gravity is a property of all matter. 1b) False. Gravity is a property of all matter. 1c) True. 1d) False. Gravity is much weaker than the electric force between atoms. 1e) True. Antigravity has not been discovered. 1f) True. The force of gravity decreases with the square of the distance. 1g) False. A planet’s gravity is determined by its mass. A non-spinning planet would have the same gravitational field. 2. Matching The process that powers the Sun and other stars Gas or dust cloud Bands of colour that result when white light is separated Ending stage of a very massive star Last shining stage of a small star Outer surface of a star expanding into space Star after its initial hydrogen fusion stops Fusion Nebula Electromagnetic spectrum Supergiant / black hole White dwarf Planetary nebula Red giant 3a) Gravity 3b) The temperature of a gas rises as the gas is compressed. 3c) The force of gravity is balanced by the increased radiation and pressure produced in the interior of the star when fusion begins. 4. Our Sun’s surface is yellow, so it is a little cooler than a white dwarf. Our Sun is also much larger than a dwarf star. Fusion is occurring in the interior of our Sun, whereas no fusion is occurring in a white dwarf. 5. A star’s fate depends on its mass. Massive stars can end up as a supernova explosions, leaving a black hole or neutron star. Intermediate mass stars form red giants or supergiants, perhaps giving off a planetary nebula and leaving a neutron star or a white dwarf that eventually becomes a black dwarf. A low mass star ends up as a white (then black) dwarf, but never starts helium fusion. 6. – A rotating cloud of gas and dust begins contracting. - The rotation rate of the cloud increases - The nebula flattens as material along the axis collapses into the centre of the object. - In orbit around the centre of the gas and dust sphere, small accumulations of gas and dust start increasing in mass. - The temperature at the core of the contracting, rotating cloud increases. - The temperature at the core of the gas and dust sphere reaches 10,000,000 degrees C. - The star “turns on”.