To investigate the time taken for the pendulum to oscillate for a time period.

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Pendulum Investigation

Aim:

To investigate the time taken for the pendulum to oscillate for a time period.

Introduction:

This experiment looks at the relationship between the length of string on a pendulum and the time taken for the pendulum to oscillate for a period.

Oscillation is the process by which the pendulum swings from one peak to the other peak and back again.

The period is the time taken for the pendulum to oscillate from one side to the other and back again.

This experiment investigates the physics of simple harmonic motion and energy transfer.

Factors:

The factors affecting the rate that a pendulum swings are:

  • The height from which the pendulum is released from -

Swinging the pendulum back from its stationary point gives the pendulum more potential gravitational energy.

Take for instance the weight of the pendulum is 20g and is released from 5cm from its stationary height, then the pendulum has 0.01 J of potential energy (m.g.h).

Doubling the height would therefore double the amount of potential energy and give 0.02 J.

Potential energy will affect the speed at which the pendulum travels and therefore will effect the rate at which it swings.

If the pendulum is released within a small distance from the normal then this factor will not really effect the period of oscillation.

It will be more effective on a physical pendulum rather than the simple pendulum as simple harmonic motion is independent from the amplitude of the oscillation.  

  • Mass of the pendulum -

Again this will not effect the time period all that much in this experiment, but in similar experiments the mass is vital.

This is a major factor when it comes to calculating the gravitational potential energy, Egpe (m.g.h) and kinetic energy, Eke (½.m.v2).

During this or any similar experiment the mass should stay constant.

  • Air resistance  -

Theoretically a pendulum should be able to swing forever at a constant speed and at a constant rate.

After all once the pendulum is pulled back and released giving it potential energy, the pendulum will convert it into kinetic energy, swing to the other side and the process should repeat itself forever.

But in reality, at Earth anyway this is not possible.

This is because air molecules get in the way of the pendulum, and when the particles of each collide the pendulum loses energy to the air molecules.

This is called air resistance and causes the pendulum to slow down with every swing.

This factor will not effect the period of oscillation by a big margin because in simple harmonic motion every period for a specific length of string is the same.

This is because as air resistance slows the pendulum it proportionally reduces its amplitude and so the time period is the same.

  • Length of string -

Length of string is a big factor regarding the affect of the rate at which a pendulum swings.

Basically the smaller the length the faster the rate because the pendulum has a smaller distance to travel.

This is because the length of string is like the radius of a circle and like in all circles the smaller the radius the smaller the circumference as the 2.π is constant and only the r is a variable.

This will be the chosen variable as it can give quantitative results, it is easy to control and measure, and it has a direct link with the period of oscillation.  

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  • Gravitational acceleration -

This will be the main force acting upon the pendulum when it is moved away from its stationary point. The gravitational acceleration on earth is constant at about 9.8 N/kg.

The gravitational force will be responsible for supplying the pendulum with energy (from potential to kinetic) to swing back and forth.

This is because it contributes to the potential energy the pendulum will posses as shown in the formula m.g.h.

If this same experiment were being conducted on the moon, the results would be quite different, as gravitational acceleration is only 1/6th of what it ...

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