Physics Ia First Draft

Laws of conservation

 The law of conservation conservation of energy is a law in physics physics which states states that energy energy cannot be destroyed nor created but changes from one form to another or transferred from one object to another. Examples of these conservations of energy can be seen in everyday life. Consider throwing throwing a ball at a stationary glass cup. The ball has potential energy which turns into kinetic energy when thrown, when the ball hits the stationary cup, the energy transfers from the ball to the cup causing it to fall over or even break. The ball losses energy as it has been transferred to the cup so the ball falls to the ground.  The laws of conservation of of energy are are among the most studied studied and practical practical laws of physics. These laws help in nding the solution of many mechanical problems. hen work is done by an external force on an object there will be a change in the total mechanical energy of the object but if the forces doing work on an object are internal!conservative" internal!conservative" then there will be no change in the total mechanical energy. hen this is the case we can say that the total mechanical energy of the object is conserved. hen an object is acted on by only conservative forces the mechanical energy may be transferred between kinetic and potential energy but the total mechanical energy which is the sum of kinetic and potential energy will remain a conserved #uantity. #uantity.

Mechanical Mechanical energy conservation in this investigation investigation $n this investigation $ will consider the mechanical conservation of energy in a pendulum. The conservation of energy in the pendulum will be conrmed, this $ knew before my experiment as $ did some research prior to my investigation and this topic was covered in class. The potential energy !the energy an object has due to its position in a force eld" and kinetic energy !energy in motion" of the pendulum will also be determined to test my hypothesis that the sum of mechanical energy is conserved for a system that includes only conservative forces. This will be done because the sum of the potential and kinetic energy e#uals the total energy. %inetic energy& 'otential energy&  Total  Total Energy Energy&&

Pendulums

 KE =1 / 2 mv

2

 PE =mgy 2

 E=1 / 2 mv + mgy

 The motion of a pendulum is a typically used example when investigating mechanical energy conversion. ( pendulum is made of ) parts a mass which is attached by a string to a pivot point. (s the pendulum moves it goes in a circular arc. $n this investigation $ will be neglecting air resistance as force acting on the pendulum because it has too small an e*ect on the pendulum which means that $ will only be assessing ) forces acting on the pendulum namely& gravity and tension. +ravity is a conservative force so it does not a*ect the total mechanical energy and tension is external force but the force of tension will not play a role in this investigation as tension always acts in a direction which is perpendicular to the mass. $n all points in the arc of the mass, the angle between motion and tension is always e#ual to - degrees so tension does not a*ect the investigation. eeing as no external force acts upon the pendulum, the total mechanical energy should always be conserved.

Experimental Design The purpose of this investigation is to calculate the potential and kinetic energy of a swinging pendulum and thereby calculating the total mechanical energy conservation of a swinging pendulum. $ will limit my investigation to / pendulum and $ will limit the study to one initial drop height and the resulting data collected. 0sing a webcam and 1ideo'oint Capture program, the swing of the pendulum was recorded. %inetic, potential and total energies were generated by spreadsheet. $ will be using the Energy per unit mass since $ have not measured the mass of the pendulum and because $ don2t need to. $ will compute the potential energy per unit mass relative to the low point in the pendulum swing3 $ will be calling this e#uilibrium height

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