Thermodynamics: Law Of Conservation Of Energy

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Introduction

In physics, the law of conservation of energy states that the total energy in an isolated system stays constant, which could not be recreated but will change to other forms of energy, e.g. friction will turn kinetic energy to thermal energy. In thermodynamics, the first law of thermodynamics states that the conservation of energy is the more encompassing system of the conservation of energy. In short, the conservation of energy is the statement of energy that can not be created or destroyed; it can only be changed or transformed from one form to another, while the total amount of energy is still the same.

In this experiment, an attempt will be made to demonstrate the conservation of mechanical energy in the swinging of
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To be able to use the recorded time in Table 1 to calculate the angular velocities of the pendulum at the lowest point, the total angular displacement ∆ of the pendulum, during which the timer is activated, has to be known. The timer could be told to be activated by the red indicator light on the sensor. Determine the value of ∆ and record it on the log sheet.

3) Switch off the photo timer. Displace the pendulum by a small angle(less than 5°) from its equilibrium position. Release the pendulum from rest and check that it is swinging on a vertical plane. Use a stopwatch to measure the time for 10 oscillations. Record the reading on the log sheet. The period T of the pendulum for “small” oscillation is now obtained.

4) Use the mass balance in the laboratory to measure the mass M of the pendulum. Remember that the pendulum consists of all components that oscillate, including the pivot block. Record the reading on the log
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Plot a graph of K.E.(kinetic energy at the lowest point of swing) against P.E.(potential energy at the highest point of swing). Your graph should be a straight line. What is the gradient of the line? What can you conclude from this? The gradient of the line is approximately 1, which means the potential energy at the highest point is equal to the kinetic energy gained at the lowest point. We can conclude that the value of the potential energy is conserved to kinetic energy during the process.

b. What are the possible sources of error for the experiment?

The possible sources of errors include:
- Reading errors while taking the measurements of the pendulum;
- Slow human reaction when using the stopwatch to record the time of the oscillations.
- Air resistance when the experiment is taken, the potential energy is converted to sound and heat energy other than kinetic energy.
- Data calculation has been rounded up to three decimal points and q was used instead of sinq to simplify the calculations.

Formal Report

a. Include your answers to Exercises 1-6 above.

Exercise 1
The angular velocity of the pendulum at the lowest point of the swing, as denoted by , can be easily calculated from the values of ∆ and the time t in Table 1 by using the

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