Search

# Investigation of the pendulum

Updated: Oct 22, 2019

Background information

The reason to the making of this experiment was to find the equation of the Pendulum and determine what affects the period the most with different constant and changeable factors such as length, angle and mass. A pendulum is an object suspended on a fixed point that can only move through given force transformed from potential energy from my hand to kinetic energy making the pendulum swing from side to side with periodic motion. Several factors can affect the period of the pendulum such as the angel from which the pendulum is let go to swing, mass hanging at the end and the length. Thus this investigation is going to give us an equation as well as show us if the period is dependent on any of the named factors.

Independent or dependent Variables (Manipulated)

Experiment one :

• Is the period depending on the angle? We kept mass and length constant, as independent variables.

Experiment two :

• Is the period depending on the length? We kept the mass and angle constant, as independent variables.

Experiment three :

• Is the period depending on the mass? We kept the length and the angle constant, as independent variables.

Experimental Controls

Experiment one :

• We used 100g as the mass and 40 cm string.

• The angel was changed between the 10 trials from 45-5 degrees.

Experiment two :

• We used 100g as the mass and 45 degrees as the angel.

• The length was changed between the 10 trials from 0,05-0,50 meters.

Experiment three :

• We used 40 cm as the length of the string and 45 degrees for the angel.

• The mass was changed between the 10 trials 50g-500g.

Equipment

Method

{1} The procedure was set up as shown in the picture with a stable apparatus and table. The thread was knotted around the metal bar and secured as well as a small knot made at the end of the thread wrapped around a chosen weight. {2} The length of the thread was measured with a cm ruler and the weight was displaced and released. {3} As soon as the weight was released the stopwatch was set to count the time taken for the pendulum to swing 10 times from side to side. {4} The time for 10 complete oscillations, t was taken using a stopwatch and the period of oscillation was calculated. The definition of period in this case can be seen in the image, where the weight is displaced from C back to C which is counted as 1 period.

Results and conclusions from the first three experiments

Experiment 1:

Table 1: shows the values from experiment one.

Graph 1

Graph 1: shows the pendulum while changing the length and having the constant weight and angle. Conclusion: the pendulum is affected by changing the length, as the period is increasing as the length is increased.

Experiment 2:

Table 2: shows the values from experiment two.

Graph 2

Graph 2: shows the pendulum, while changing the angle and having the constant weight and length. Conclusion: the pendulum is not affected by changing the angle, as the period is not changing when changing the mass.

Experiment 3:

Table 3: shows the values from experiment three.

Graph 3

Graph 3: shows the pendulum while changing the mass and having the constant length and angle. Conclusion: the pendulum is not affected by changing the mass, as the period is not changing when changing the mass.

Table 1.1: shows the values from table 1, but with the square root of the length.

Graph 1.1

Graph 1.1: shows the linear line of chart 1 made by the equation T = 2l

Conclusion= a straight, linear, line is achieved by taking the square root of the length.

Analysis

As shown in the graphs, the pendulum and its time is affected when just the length factor is manipulated and turned to a dependent variable from an independent. In graph 1 it is shown that the period of the pendulum was increased when the length of the string was manipulated, thus the conclusion is that when the string is longer, then the pendulum has a longer distance to travel and that increases the period. The period is not affected by the other factors which were investigated.

In graph 2 it is shown that the time first increases with small amount, to then decreases to approximately the starting point. But as the time changes are that small, the conclusion can be drawn that the period of the pendulum is not affected by changing the angle. Thus this goes against our hypothesis which was that the time should have increased when the angle was as large as 45 degrees considering the pendulum would have a longer distance to travel and the period should have decreased when the angle would have been as small as 5 degrees.

In graph 3 it is shown that the mass is not affecting the period so much either as a similarity to graph 2.

Errors

The dependent variables in this experiment can have manipulated the outcome as they are measured by using the eyes which can give an uncertain value. The length of the thread can therefore been a little shorter or longer than it should have been, giving another result than if it would have been exactly measured. A more stable table would have been useful as well as more accurate positions of the thread on the metal stand. It would also been good to investigate how a magnet would have affected the pendulum as magnetism can disturb the gravity and moreover affect the period of pendulum.

81 views

See All