2216994
Description
Flashcards by James Jolliffe, updated more than 1 year ago
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Created by James Jolliffe
over 9 years ago
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| 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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