To investigate the factors that affect the time of swing in a simple pendulum, using a small weight and a length of string attached to a fixed point.

Aim: To investigate the factors that affect the time of swing in a simple pendulum, using a small weight and a length of string attached to a fixed point.

Background Information: Dictionary Definition:
n1 a weight suspended so it swings freely under the influence of gravity. 2 such a device used to regulate a clock mechanism.

”Pendulum, a mass, called a bob, suspended from a fixed point so that it can swing in an arc determined by its momentum and the force of gravity.”

-Columbia University

A pendulum can be defined as anything suspended from a fixed point that can swing in an arc. This can be anything from a watch on the end of a string, to a huge demolition crane. These types of objects are
seen often around the world. A pendulum generally
swings from one height, gains momentum, follows an
arc through and decelerates at it goes against gravity
back up to an altitude similar to that of its release
point.
        The object at the end of the pendulum is called
a bob. The length of the pendulum is from the point of
suspension to the centre of gravity of the bob. The
time taken for the pendulum to swing from one side
to the other is called the Period of Swing.

Hypothesis

My prediction is based on 3 main factors:
        Length of string
        Mass of Pendulum
        Angle of release

Firstly, the length of the string will cause the pendulum
to have to travel further to complete a full swing. The
size of the arc will correspond to the length of the string. This would then in turn cause the period of swing
to increase.

The mass of pendulum would also have an affect on the period of swing. Generally, heavier weights will cause the time to increase. This is because the heavier mass will cause an increased velocity, making the pendulum to swing further.

Finally, the angle of release will have the biggest effect on the time. If the pendulum is released from 10º, then the arc will be small. If the pendulum is released at 40º, then the effect of gravity on the weight will last longer than if it was released from a smaller angle, making the arc bigger. This will cause the weight to swing faster, causing the period of swing to increase.

Method

         ∙ Apparatus

1 weight
1 clamp stand
2m length of string
Stopwatch
Protractor

Meter rule

Set up the equipment as follows:

Set up the clam stand, with the horizontal pole sticking over the table edge. Loop one end of the string in such a fashion that it may be freely adjusted in length. Attach the weight to the end of the string, so that it hangs freely over the edge of the table, without slipping or causing the clamp stand to topple. If needed, place a few heavy items on the base of the clamp stand to keep it upright. The equipment should now be set up as shown in the diagram.

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Meter rule

∙ Variables

The following is a list of the variable that will be used in this experiment:

Weight Mass:

Angle of release: 20°

Length of string (cm): 10, 20, 30, 40, 50, 60, 70, 80, 90, 100

Number of swings per reading: 10 (time/10 to give accurate reading)

To keep this a fair test, the mass of the weight will remain the same, alongside the size and shape. The same string and clamp stand will be used. The position of the clamp stand will not be altered. The angle or release will remain static throughout the experiment.

∙ Average calculation

To ensure that an accurate result is recorded, the average of multiple results/swing must be taken.

i. The period of swing will be calculated by finding the average from 10 swings. This will compensate from any human error that occurs.
Calculation: Time / 10

Eg. 10.5s / 10
= 1.05s

ii. The average period of swing will also be calculated from an average. Once (i.) has been completed and the experiment has been repeated, then an average period of swing will be calculated.
Calculation: PoS1 + PoS2 / 2

Eg. 1.05s + 1.07s /2
= 1.06s

a. Note: If the experiment has been repeated more than twice, then the division will change t represent the amount of repetitions.

∙ Conducting the experiment

1. Take the meter rule, and adjust the string so that it corresponds to the length of the variable you are measuring. Note: The length must be measured from where the string meets the end of the clamp, to the centre of the weight.

2. Place a protractor underneath the end of the clamp stand, so that the 90° angle mark is directly behind the string, which is hanging freely straight toward the centre of gravity.

3. Ensure the stopwatch is set to 0:00. Then, with the assistance of another person, grasp the weight and pull it back so that the string is tilted 20°. This should mean the string is either at 110° or 70° mark on the protractor.

4. Simultaneously release the weight and start the stopwatch. One swing counts where the pendulum swings from one side to the other, then back again, reaching its original point. Let it do this 10 times, then stop the stopwatch. Record this time in the table.

5. Repeat this procedure, so that you have 2 results for this. Work out the average (mean) of the 2 results. Note: To make the results more accurate, repeat this more then twice. Then remove any phantom results, and calculate the average from the remaining.

6. Repeat the above for each of the given variables.