Key Physics Topics 0.0 / 5 ? PhysicsNewtons LawsGCSEEdexcel Created by: xerinxCreated on: 10-03-19 13:53 Newton's First Law A resultant force is needed to make something start moving, speed up or slow down If the resultant force on a stationary object is zero, the object will remain stationary If the resultant force on a moving object is zero, it will carry on moving at the same velocity 1 of 10 Newton's Second Law Acceleration is proportional to the resultant force The larger the resultant force acting on an object, the more it accelerates Acceleration is inversely proportional to the mass of an object Therefore, an object with a larger mass will accelerate less than one with a smaller mass The formula for the second law is: F = m x a 2 of 10 Momentum p = m x v momentum(kg m/s) = mass(kg) x velocity(m/s) The greater the mass or velocity of an object, the more momentum the object has Momentum is a vector as it has a size and direction 3 of 10 Changes in Momentum A force causes momentum of an object to change A resulatant force of an object causes it to accelerate ( Newton's 2nd Law) Acceleration is a change in velocity over time, so: force = mass x change in velocity / time This means a force applied to an object will change its velocity Mass x change in velocity is equal to change in momentum, so: force = change in momentum / time 4 of 10 Energy Stores The types of energy stores are: Kinetic Thermal Chemical Gravitational Potential Elastic Potential Electrostatic Magnetic Nuclear 5 of 10 Kinetic Energy When an object is moving, it has energy in its kinetic energy store You can find the energy in a kinetic energy store using: kinetic energy = 0.5 x mass x ( speed x 2 ) 6 of 10 Conservation of Energy Energy is never created or destroyed Energy can be stored, transferred between stores, and dissipated - but it can never be created or destroyed. 7 of 10 Efficiency Usefull devices can transfer energy from one store to a usefull store However, some of the input energy can dissipate into the surroundings You can calculate the efficiency of any device using: efficiency = useful energy / total energy supplied This gives you a decimal so to find a percentage you need to multiply the answer by 100 8 of 10 Energy Resources - Renewable Renewable resources will never run out as they can be renewed as it is used Most of them do damage to the enviroment but not as much as non-renewable resources They include: Bio-fuels Wind The Sun (solar) Hydro-electricity Tides 9 of 10 Energy Resources - Non-Renewable Non-renewable energy resources are fossil fuels and nuclear fuel They provide the most of the worlds energy They are natural resources that form underground over trilions of years The main fossil fuels are oil, coal and gas They emmit carbon dioxide into the atmosphere when they're burned, which adds to the greenhouse effect, and contributes to global warming 10 of 10
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