# Physics

 energy something that is need to make things happen. Energy is the ablitiy to do work Basic yet important energy points (5) Energy cannot be created to destroyed All living things have and need energyenergy existis in different formsenergy canchange formsEnergy is not a substancew it does not take up space and cannot be weighed Measuring energy Energy is measured in joules. Joules is a very small unit so kilo joules are offen used. the symbol is J or kJ Two main forms of energy Potential energy (stored energy) and active energy Potential energy types Gravitationalelastic nuclearchemicalmagnetic(GENCM) Active energy types Soundheatradiant (light) eletrical kinetic(SHERK) Law of conservational energy Energy cannot be created or destroyed it only changes from on form to another. The total out put remains constant as the input Weight Force pf gravity pullling towards the earth. It is gravity times mass Force a push or a pull Measuring forces Force is measued in newetons Four types of forces Lift, gravity, thrust, and friction Un/balenced forces when forces sre balence the object is stationary or traveling at a constanst speedWhen forces are unbalenced the oject is acclerating or decelerating Net force When net force is 0 the forces are balenced. When net force isn't 0 the forces are unbalenced Calculating net force/resulant force If forces are acting in the same direction you add them togetherIf the forces are acting in the opposite then we subtract the the bigger value from the smallerthe object will move in the direction of the bigger force Distance time graphs Distance on y-axis, time on x-axisConstant upwards slope means travelling at a constant speedStraight line means stationarycurving upward means acceratingcurving downwards means decelleratingdownwards slope means returning to startslope is speed, rise over run Speed time graph speed y-axis, time on x-axisupwards slope - acceratingdownwards slope - decleratinghorizontal on base - stopedhorizontal in air- constant speedtotal distance is area under the line Accleration due to gravity when an object falls verically it accerates due to gravity. This accerationna of a free falling object is called acceration due to gravity. This acceration due to gravity has a value of 9.8ms-2 but in calculations it is rounded to 10ms-2 Terminal Velocity when objects fall from a large height, the do not continually accerate but eventually moves at a constant speed. This is beacuse air resistance increases as speed and balences out the down wards force of gravity, and the object cannot acclerate Discus how the speed of a car effects the damage in a crash Kinetic energy is proportional to the square of speed when speed is doubled the kinetic energy is quadrupled by factor 4. Therefore the impact is heavier and tyhe more damage AuthorTaz ID112517 Card SetPhysics Descriptionother physics stuff Updated2011-10-27T07:10:52Z Show Answers