GCSE AQA Physics - Unit 2

Description

The second part in the epic trilogy that is GCSE AQA Physics. Dr. Physics and his band of Physicists have beaten the evil of Cosmic Microwave Background Radiation, saving the land of Physika. But an ancient evil is awakening, and the Sun will soon become a white dwarf...
Flashcards by James Jolliffe, updated more than 1 year ago
 Created by James Jolliffe almost 9 years ago
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Resource summary

 Question Answer What are forces measured in? Newtons If there are multiple forces acting on an object, they can be replaced as a single force, known as the ____________ ________. Resultant Force If there is a non-zero resultant force acting an an object, what effect will be observed? An acceleration in the direction of the resultant force How do you work out the speed of something? Distance/Time What extra factor does velocity have over speed? The direction What does the slope/gradient of a velocity-time graph show? The acceleration The area underneath the line in a velocity-time graph represents ______ __________ ____________ ________________. The total distance travelled Friction occurs when... - An object moves through a medium, e.g. air or water - Surfaces slide past each other How do you work out the stopping distance? Thinking distance + Braking Distance What two forces do all falling objects experience? A downward force, called weight (W) An upward frictional force, e.g. air resistance or drag through a fluid (R) What is meant by terminal velocity? Constant speed reached when the upward resistive force balances the downward force (weight) What is the name given to energy that is stored in an elastic spring? Elastic potential energy What is 'work done' (in terms of energy)? Energy transferred what is the gravitational potential energy? The energy an object has due to its vertical position in the gravitational field What is meant by the phrase 'conservation of momentum'? Total momentum before = total momentum after An electric current flowing through a circuit is... A flow of electric charge An electric current will flow through an electrical component is there is a... potential difference (voltage) across the ends of the component. What two factors affect the amount of current that flows through a component? - The potential difference across the component - The resistance of the component As the amount of light falling on a light dependent resistor (LDR) increases, the resistance... decreases. As the temperature of a thermistor increases, its resistance... decreases. As the temperature of a filament lamp increases, and the bulb gets brighter, then the resistance of the lamp... increases. Why is this? This is due to the greater vibrations of the metallic ions in the filament wire gradually preventing the flow of free electrons. TRUE OR FALSE: A diode allows current to flow through it in only one direction. TRUE This is because it has a very high resistance in the reverse direction What colour is the: Earth Wire? Neutral Wire? Live Wire? Green and Yellow Blue Red Name two devices that give protection when an electrical fault occurs? Fuse Circuit Breaker Residual Current Circuit Breaker What is the name of the rate at which energy is transferred? Power What is the amount of electrical charge that passes any point in a circuit measured in? Coulombs What is the Relative Mass and Relative Charge of: A Proton A Neutron An Electron Proton: RM= 1 RC= +1 Neutron: RM= 1 RC= 0 Electron: RM = 1/2000 RC= -1 What are isotopes? Atoms of the same element that have different numbers of neutrons What do isotopes of atoms that have too many or too few neurons form? Unstable Nuclei What is radioactive decay known as? Background radiation What happens in Alpha Decay? The original atom decays by ejecting an alpha particle from its nucleus. An alpha particle is a huge particle. It's identical a helium nucleus, consisting of two protons and two neutrons. What happens in Beta Decay? The original atom decays by changing a neutron into a proton and an electron. The electron emitted is called a beta particle, with the symbol β. What may happen when radiation collides with neutral atoms or molecules in a substance? The atoms or molecules may become charged due to electrons being 'knocked out' of the orbiting structure. This leaves the atoms or molecules as ions, or as charged particles. What is the charge of an alpha particle and a beta particle? +2 for Alpha Particle -1 for Beta Particle Alpha Particle: What is its ionising power? What does it take it be stopped? Is it affected by Electric and Magnetic fields? Strong Stopped by paper, skin or 6cm of air Yes, but opposite to beta particles Beta Particle: What is its ionising power? What does it take it be stopped? Is it affected by Electric and Magnetic fields? Weak Stopped by 3mm of aluminium Yes, bent strongly, but opposite to alpha particles Gamma Particle: What is its ionising power? What does it take it be stopped? Is it affected by Electric and Magnetic fields? Very Weak Reduced, but not stopped by lead No What is the half life of a radioactive isotope? A measurement of the time it takes for the rate of decay to halve OR The time required for half of the original population of radioactive atoms to decay What is Nuclear Fission and what is it used for? The splitting of an atomic nucleus. It's used in nuclear reactors to release energy to make electricity. What is meant by the term 'chain reaction'? Neutrons released from the initial reaction go on to interact with other nuclei producing even more neutrons each time. What is Nuclear Fusion? The joining together of two or more atomic nuclei to form a larger atomic nucleus. What are the steps in a star's formation? Stars, like our sun, form when enough dust and gas from space are pulled together by gravitational forces, which always attract each other. This forms a nebula where a protostar is then formed. Forcing material together increases the temperature and density, and nuclear fusion reactions start releasing huge amounts of energy. Eventually the forces balance to make a star stable. The newly formed star becomes a main sequence star. What happens when a star about the size of the sun runs out of hydrogen? 1. The Star leaves the main sequence and becomes a red giant 2. It continues to cool before collapsing under its own gravity to become a white dwarf. 3. It continues to cool and loses its brightness to become a black dwarf. What happens when a star much larger than the sun runs out of hydrogen? 1. The star leaves the main sequence and becomes a red super giant. 2. It cools but shrinks very rapidly and explodes as a supernova. This explosion releases massive amounts of energy, dust and gas into space, and forms elements heavier than iron. 3. Depending on the precise mass of the remnants either a neutron star or a black hole is formed. 4. The dust and gas form new stars.

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