# Investigation on &#145;The Law of Conservation of Energy&#146;

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Introduction

Investigation on 'The Law of Conservation of Energy' Background Information The Law of Conservation of Energy states that energy can neither be created nor destroyed: it is always changed from one form to another. If an object is raised above the ground it acquires Gravitational Potential Energy (GPE). The amount of GPE depends upon the mass (m), the force of gravity (g) and the vertical height the object is lifted (h), where: GPE (in joules) = mass (in kilograms) x force of gravity (10N/kg) x height (in metres) or GPE = mph If an object is allowed to fall under the influence of gravity, it acquires Kinetic Energy (KE). The amount of KE depends upon the mass (m) and the velocity (v) where: KE (in joules) = 1/2 mass (in kilograms) x velocity2 (in metres per second) or KE = 1/2mv2 Plan I have to use a dynamics trolley in order to investigate and prove the Law of Conservation of Energy. To do this I will set up a ramp and a let the dynamics trolley roll down it, measuring the energy at the start, and at the end of its movement. The Law of Conservation of Energy states that energy is not lost when we do something, it is merely changed from one form to another. ...read more.

Middle

I can then use this (and the mass) to find the KE of the trolley. Results Note: All units have been converted so that they fit the original equation. (e.g. centimetres to meters) Height of ramp (h) 10cm 20cm 30cm GPE at start (in J) 0.540 x 10 x 0.1 = 0.54 0.540 x 10 x 0.2 = 1.08 0.540 x 10 x 0.3 = 1.62 Distance between dots (d) 2.5cm 3.5cm 4.5cm Velocity of trolley (in m/s) 0.025 / 0.02 = 1.25 0.035 / 0.02 = 1.75 0.045 / 0.02 = 2.25 KE at end (in J to 2d.p) 0.540 / 2 x 1.252 = 0.42 0.540 / 2 x 1.752 = 0.83 0.540 / 2 x 2.252 = 1.37 40cm 50cm 0.540 x 10 x 0.4 = 2.16 0.540 x 10 x 0.5 = 2.7 5.5cm 6.5cm 0.055 / 0.02 = 2.75 0.065 / 0.02 = 3.25 0.540 / 2 x 2.752 = 2.04 0.540 / 2 x 3.252 = 2.85 Analysing Here is a graph to show the relationship between the height of the ramp and the trolley velocity. This graph shows us that as the height of the ramp increases then so does the velocity of the trolley at the end of the ramp. ...read more.

Conclusion

The only explanation I can come to for this result is that there was a gust of wind which pushed the trolley, or that when I was releasing it I accidentally pushed it slightly. There are factors that you could change in order to obtain a more accurate result these include: 1) Do the experiment in a vacuum. This would avoid any chance of wind affecting the trolley, and also eliminate air resistance. 2) Make the wheels and bearings of the trolley so smooth that there is no friction. This is highly implausible, but it would increase the accuracy of the result. 3) Use a laser timing system so that the ticker tape cannot cause friction as it passes through the ticker timer, or air resistance as it lags behind the trolley. 4) Measure all results to a large degree of accuracy. This would obviously improve results. All these methods could be used, although they are very extreme and somewhat irregular. They would also need very sophisticated equipment, which could probably be used for a better purpose. Considering the equipment I used, and the circumstances in which I worked, I believe that my results are adequate to prove that energy is converted from one form to many others, as the trolley moves down the ramp. Mike Games GCSE Physics Coursework ...read more.

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