physic investigationTitle : A study of Principle of Conservation of Energy in terms of Gravitational Potential Energy and Kinetic Energy.
Problem: How does the change of gravitational potential energy affects the kinetic energy?
Objective : To investigate the relationship between the gravitational potential energy and kinetic energy.
Variables :
Manipulated variable : The height at which trolley is placed from the reference point
Responding variable : The velocity of the trolley down the ramp
Constant variable : The mass of the trolley.
Hypothesis : The higher the height at which the trolley is placed from the reference point, the higher the velocity of the trolley down the ramp.
Operational definition : 1. Kinetic energy can be determined from the ½ mv², where the maximum velocity of the trolley is determined by ticker tape.
Apparatus and Materials : Ticker timer, ticker tape, trolley, ramp, 12V a.c. power supply, retort stand, retort clamp, bosshead.
Introduction and Theory : According to the Law of Conservation of Energy, the energy in a system may take various form and may be interchanged among the components of the system, but there is never any net gain or net loss of energy by the system as a whole. An object of mass, m, at a height, h, above the ground has potential energy PE=mgh. If the object falls, its potential energy decreases. As it falls, its velocity increases, so its kinetic energy (KE= ½ mv2) also increases. By the law of conservation of energy, the sum of the potential energy and the kinetic energy must remain the same. It follows that the sum of the changes in potential and kinetic energy must equal to zero:ΔPE=Δ KE∴ mgh =½ mv²In this experiment, in order to prove that the total gravitational potential energy is converted to kinetic energy, hence abiding by the law of conservation of energy, height, h, at which trolley is placed from the reference point represents the gravitational potential energy possessed by the body. When the trolley is rolled down the ramp, the gravitational potential energy is converted into kinetic energy, where the kinetic energy is calculated from the velocity of the trolley down the ramp.
Procedure:
The mass of the trolley,m is determined by using an electronic balance and the height of wooden blocks are determined using metre rule.The apparatus is set up as shown in the diagram above.The ticker timer is switched on and the trolley is released at the height of 0.200m.The maximum velocity is determined from the ticker tape.The loss of the gravitational potential energy of the trolley is calculated from the formula, PE=mghThe kinetic energy of the trolley is ½ mv².The values of the kinetic energy and potential energy obtained are compared.Steps 3-7 are repeated placing the trolley at different heights of 0.300m, 0.400m, 0.500m, 0.600m, 0.700m, 0.800m, and 0.900m.The data obtained is tabulated and a graph of kinetic energy against gravitational potential energy is plotted.
